If you’ve ever been in a position where you weren’t able to relicense an entire project as GPL, or were developing for a platform that doesn’t allow LGPL3 libraries to be used because users can’t replace the LGPL3-licensed binary (ios, android, game consoles, proprietary hardware), which I’m sure many people with programming careers have experienced at some point, you’ll quickly find that any copyleft-licensed library is effectively useless to you.
I would wager that those who have had to deal with that before are much less likely to use a copyleft license for future projects.

There’s also a lot of small projects where the developer doesn’t care about licensing. They just want the code out there, and for anyone to be able to use it, as long as they get some recognition for making it.

Most people aren’t lawyers, and don’t care enough to read all the different licenses and compare them all. They pick the simplest one that ensures anyone can do anything with it, and they aren’t held liable for anything.

Apache is too full of legalese for most people to bother reading. BSD has different versions which make it more complicated to pick which one you want. MIT has much less confusion about versions (there are different versions, but most people associate ‘MIT license’ with the most common one).

And then the existing popularity helps lock in a license choice once you’ve picked a license category. “If MIT is good enough for ‘x’, it’s good enough for me.”