Why does the url of a Google result page with only 2 results need to be so long?

Because the URL is determined by your search terms, not by the results your search produces.

There’s a data structure in programming called key-value storage. It’s also known as a dictionary where for any given key, there is a result that is paired with it. They take the key and run it through something called a hashing function which turns normal text into what looks like gibberish. This makes it lightning fast for Google to perform lookups. If it had to crawl through every possible search combination to find your result each time, it would take days/weeks/years to find you search results.

Let me just add that the actual answer is probably much more complicated, and I could be wrong about some of my assumptions. The search team for Google are likely some of the smartest men and women on the planet.