That's normal in markets and it even makes sense.
Think about it: shouldn't the market be funded by charging fees to the extremely wealthy participants? The alternative is that it's taxpayer funded, which is a tax subsidy to extremely wealthy participants.
Most if not all stock markets are for profit corporations making a lot of profit. They could have api fees at 0 and still make a profit.
Several such APIs include the equivalent data for US markets in their free tier, for personal use.
Only the extremely wealthy participate in the UK? That is most certainly not the case in the US, where your average salaried employee has most of their retirement invested in the market
Seems like a bit of a false dichotomy- other alternatives are regulatory requirements or taxes that force or allow the api to be provisioned