If they can put a man on the moon, why can't they [fill in the blank]?

Keep people from building on the seashores, where the houses get blown down in every big storm?

Keep giant banks from stealing from the people?

Keep big companies from polluting the atmosphere?

Stop global warming?

End hunger in the world?

Bring peace to the world?

…make 100% effective, cheap and reversible birth control.

Sending a man to the moon was the result of billions of tax payer currency being pumped into the state funded space programme without any intent of making money, but purely out of geopolitical and military reasons. The evil soviets could not be allowed to win the space race.
Just look at today’s private space companies. Space tourism is what they want. And that in baby steps. Using technology created by government employed scientists and engineers. Had the US just waited for private companies to go into space and to the moon, the Soviets would have won the space race to the moon, too, in addition to having the first object in space, the first animal in space, the first man in space, the first woman in space, the first black man in space, the first space walk, the first picture of the back side of the moon, the first landing of a probe on the moon and the first space station. Chances are the US would have never made it into space at all, because private companies do not have the motivation nor the funds to take the risk of space pioneering, because they need to make money from day one, and one rocket exploding on the launchpad or during ascent, as it happened many times, would have meant instant bankruptcy for any company.
Point is, you can not compare commercial products like cars, pills, etc. with government funded development projects, because in terms of resources and motivation, the latter vastly outperforms the former.
As for your examples, the answer is simple: lack of motivation. Fuel in the US was dirt cheap and therefore there was no demand from the customers of american car manufacturers to develop such vehicles. (Of course, elsewhere on the planet, they are developing fuel efficient cars, like this 235mpg(us) VW.)
Larger bills encourage more spending, so why would they want to hand out smaller values?
And why make a skinny pill that actually works? The customer would use it just once, or once in a year. Better to sell pills that do not work at all but make gullible customers, which are plentiful, buy them again and again.

Why can’t they:

Provide affordable insurance?
Find a cure for cancer?
Create appropriate punishment for rapists and pedophiles?
Quit making movies in 3D?

Quit making movies in 3D??? LOLOL!

<takes a bow> Thank you, thank you, I’ll be here all week.

…put more people on the moon and create a working base there?

Sad aside: It won’t be long before all the men who walked on the moon and the scientists who worked on the Apollo project will all be dead.

Create an electric power grid that can effectively distribute and store energy from solar and wind power.

^That is a very good idea.

Make Rubik’s Cube world records illegal?

…have decent cell phone service at Tahoe?

lower the cost of water desalination

Keep funding NASA today

..maintain the separation of church and State.

Why can’t “they” manage the budget and create a living wage above $8 an hour and find a way to end hunger and poverty for all?

… come up with a standardized gender-neutral pronoun?

… come up with a standardized plural “you”, so we can finally celebrate the death of “yinz”, “y’all”, and “youse guys”?

Yeah, and all that other stuff about healthcare, poverty, and continuing the space program.

…make customer service worth having.

ask more intelligent questions on Fluther.

….find a cure for diabetes? I really miss eating fast food once in a while.

enter the dark side of uranus.
gag #759 involving the arse-ended planet.

If they can put a man on the moon,

Then, why can’t they find a cure for cancer?

…Establish once and for all who this mysterious “they” is?

@syz Separation of Church and State is so very difficult because the State feels that it should be involved in everybody’s business. The tendency for political entities is to grow beyond their original scope and fill the entirety of the political vacuum at their disposal.

. . . make a pill that really does make your dick bigger.

not for me, of course. i have a, uh, friend who is really interested in finding one . . .

@Blondesjon We believe you…

just slice your penis off and replace it by a horse’s

…put them all there?

Seriously though:
...make mammograms not so horrendous.
...ban oil and gas use.
...make flying cars.
...make all governments/governing transparent.
...tell us how they get the caramel in to a Caramilk bar.

legalize marijuana for medical use, recreational, food supply, clothes, bio-fuel, ect.

use our own resources, therefore becoming less reliant on other countries.

tell the truth.

Why can’t they put Newt Gingrich there ?

@dabbler FTW!!

@wundayatta Quit making movies in 3D??? LOLOL!

Seriously though, yeah.

Also why can’t they make giant pillows that could fly and take me to work in the morning? I could sleep on the pillow during the whole trip, and that would rock. But noooooooo, we have to go out and study outer fuckin space.

@ragingloli I don’t think anyone would really want that..

@Plucky Flat-out banning oil and gas would be catastrophic. Supply chains are very heavily dependent on gasoline and/or diesel engines; you would be looking at food riots within days, widespread starvation within weeks. Millions would be dead or dying within two months.
Manufacturing would also be destroyed, for the same reasons: no way to get raw materials, no way to ship them out. You’d be back to sticks with sharp rocks on them once your old tools break. And you’ll need those tools to eke out a meager living on the patch of dirt that you’ve managed to grow things on.

Better a gradual transition. Give people time to come up with viable shipping alternatives.

@Nullo Well, I know that. Of course a substantial amount of work would need to be done before outright banning it. I did not mean to do it overnight ..humans didn’t get to the moon in one instant.

Cure cancer

@Plucky The trick is to come up with a better alternative to petroleum products. When you’ve got a mode of transportation that is more efficient than the standard fleet of diesel trucks, with no astronomical startup cost, companies will be stumbling over themselves trying to get it.
Watch out for the market turmoil that’ll follow when the oil companies start losing market share. That’s gonna bite.