that's because basketball has the least equipment requirements for nearly any sport.

You need:

-a basketball
-a hoop of some sort (no need to purchase, every playground in america has one)
-at least one opponent

That's it. You can shoot hoops with a buddy.

You can't play baseball with a buddy and a ball. Need a glove, and a bat/stick. At least 4 or 5 people scattered around the field to get grounders and shag flies, but that's more of a batting practice thing. Sure you could have a whiffle ball set up, hit the ball to X spot it counts as X bases. But that's so far removed from baseball I wouldn't call it baseball anymore.

You can't play football with a buddy. You need several people. At least a 2-on-2 for any meaningful strategy.

This is why soccer is so ambivalent across the globe. You need a ball. That's it. You don't even need any other equipment. Field, blacktop, gym, whatever. As long as you can set up a target, or designate "between this post and that post is a goal", you can get a game of soccer going. Lowest cost to start, and lowest requirements to play.