Going to Apple's site, where it allows the user to pick a carrier or choose unlocked, they are all the same.

I thought all the major carrier did away with phone subsidies years ago so they could advertise lower monthly service fees, when those prices were becoming too high.

My phone is still subsidized, but it's through work, so I'm not the one paying the monthly bill. I didn't even think that was still an option for the average user buying on their own. Before switching my phone over to work, I had been buying unlocked phones at full price for a few years.

With TMobile when I upgraded they gave me 1000$ incentive in 24 month increments.

So yes they do offer "cheaper phone prices" but of course you are locked to their expensive plan for years.

Verizon offer the exact same thing. They just unlock phones after 60 days (in fairness they have to, but still, they seem to be doing just fine)

why do they have to? is it just verizon or do others have to do unlock it after 60 days too?

It goes way back to when some 700 MHz LTE spectrum was auctioned off in 2007. Before the auction and before the FCC finalized the rules that would apply to the spectrum the FCC commissioners were circulating drafts of rules they were considering. One of the drafts was proposing open access rules.

Google wrote to the FCC and made a binding commitment to bid at least $4.3 billion if the final rules included certain open access rules. The FCC then included those rules, thus guaranteeing they would get at least $4.3 billion.

Verizon outbid Google and so got that spectrum along with those open access requirements, which included no SIM locking.

In 2018 Verizon, citing fraud concerns, asked the FCC to relax the no locking rule. The FCC agreed, allowing a 60 day lock.

Verizon does but over 36 months.

did they say explicitly who it's cheaper for?

Getting AT&T to unlock an iPhone (or buying one unlocked from Apple) is little more than a formality. It's the $50 pre-paid phones you can pick up from Wal-mart that they don't want to unlock.