Why in pro American football, can't a fumble be advanced within two minutes of half or end?

To prevent last ditch efforts where a team would intentionally fumble the ball to keep the play going.

You still have the ability to lateral the ball back to teammates, but losing control of it won’t help you advance.

There was a great player for many years for the oakland raiders named Dave Casper. He was a tight end. In a really close game, he caught a pass, as he was nearing the endzone for a touchdown, he was tackled from behind. Realizing he wasnt going to be able to score, he fumbled the ball forward, into the end zone, hoping his teamate could fall on it for a touchdown.The rule is called “the casper rule”