In a US where a large population is covered under the one umbrella, it is much simpler to go with somebody like Stripe.
So the question, what solutions are available for a Startup to consider when setting up in Europe?
Further, the rules in Europe for selling stuff is not that diverse, for instance you need to collect VAT and pay that to your countries' tax department because all the countries have a treaty for that.
Stay away from PalPal, they are a US company that plays political games, freeze your account if they can find anything on you that they don't like. They also have corrupt, arrogant and hypocitical puritan issues.
Keep in mind that people from certain countries prefer additional solutions. Talk to your customers and they will tell you which payment options besides credit cards they wish to use.
In contrast to others, we've got a good relationship with Paypal as well, but we don't use them for normal credit cards because they ask too much.
Expect to interface with more than one payment platform down the road, because there is not one platform that does everything.
But starting with credit cards only and Saferpay is a good first choice.