Predictable results, familiar feel, and the accepted vibe.
It's kind of the same reason construction contractors buy white Chevy or Ford pickup trucks.
Being factory mass-produced instruments, Fender basses have a stack-up of variables. Most are pretty darn acceptable, some stink, some are extraordinary. Your job is to play long enough to find and keep a few of the extraordinary ones.
After that journey, you'll likely still end up gigging something a tad more boutique, because the typical Fender basses won't be "good enough" for your tastes anymore, and the extraordinary ones you won't want to risk losing.
It's kind of the same reason construction contractors buy white Chevy or Ford pickup trucks.
Being factory mass-produced instruments, Fender basses have a stack-up of variables. Most are pretty darn acceptable, some stink, some are extraordinary. Your job is to play long enough to find and keep a few of the extraordinary ones.
After that journey, you'll likely still end up gigging something a tad more boutique, because the typical Fender basses won't be "good enough" for your tastes anymore, and the extraordinary ones you won't want to risk losing.