In my experience, you couldn’t just setup an account and start selling, you had to contact their sales team and they let you know if they want your business.

Stripe has no real competitor.

It has lots of competitors. They bought out LemonSqueezy exactly because it was a competitor that quickly gained a lot of mindshare.

Polar.sh is another one.

The thing you're talking about with Paddle is just checking you're not selling offline, physical stuff.

Mollie might be a direct competitor

Isnt Mollie Europe only?

Mollie seems to only provide services to business based in European Economic Area, Switzerland and the UK [0], so yes?

[0]: https://help.mollie.com/hc/en-us/articles/115002116105-Can-I...

And they also have a minimum turnover limits. They rejected us as too small.

Stripe is trialing a MoR solution (managed payments) right now.