Adyen has resellers. Mollie is one example, they do have. Get Started and no lower limit. These smaller parties rely on the bank license of Adyen

I wish more companies would try to serve tiny shops at the same time they serve multi million euro companies. The requirements for the two are very different, as is the support and customer care requirement. Integrating directly with Adyen as a small business is like running a kubernetes cluster on AWS to host your blog, except they'll have even less time for customer support to spend on your tickets when things don't go right.

Platforms like Stripe where anyone can sign up at any time drive up prices because the amount of low-profit companies needs to be offset by the companies making more. Great for small startups but a bad deal for major companies.

Stripe has also been criticised for forcing growing companies into enterprise plans the moment they hit certain growth numbers. That's one way to keep the business profitable, but it's not necessary if you only take on businesses that are already profitable enough dedicate a sales team onto.

At some point you realize that your smallest customers generate the least value but require the most support.

Shedding low value users to others makes you stronger and them weaker.

What are these plugins? Could any business choose to use one, or are they highly specialized?

Like with everything in business and engineering, there's a tradeoff. My previous employer used Adyen as major payment provider (for quite some time, too). Their cost structure is sensible, the payment methods they support are convenient[ß], and their functionality is reasonably solid even in the edge cases. But everyone who maintained the payment service kept cursing Adyen for their awful APIs. The python runtime powering the old system had to carry an unmaintainable and effectively abandoned library to be able to process the Adyen payment gateway messages.

From what I understand, Stripe's main value proposition was: "how can we make this gnarly, confusing and complicated system an easy-to-use service that does NOT require the end-user to internalise the entire payment provider state transition universe?" That is obviously a valuable service, but is it valuable enough to charge an ongoing rake of nearly 300 basis points?

ß: for some weird reason people still insisted that they absolutely must be able to pay with Paypal. 2+ years of fighting cross-corporate politics + KYB and still having to stomach insanely high commissions left a properly bad taste.

Another reason is their competitors didn't get it the value prop because everyone had been competing on rates, and little thought given to developer experience... early on a lot of Stripe's competition's apis used fixed field text as the format for transactions.