One obvious answer is that Stripe has name recognition and fame, which means they can afford to charge more and get away with it. And smaller companies have an incentive to prioritize growth and user acquisition over immediate profit.

But what other tradeoffs are you implying there to be? I understand in a vague sense that payment processors deal with a lot of ugly behind-the-scenes stuff like mind-boggling varieties of frauds, dispute resolutions, regulations, etc., but what exactly is the difference in this specific case, and how might it affect a potential user in practice?

Yes, want to understand the trade off and would like to know what the challenge is in integrating directly with a payment provider that is closer to the networks / banks. I love Stripe for how easy it is to get started with but I am looking for opportunities to save cost further but getting closer to the acquirer

I dunno, the OP may want to work with a processor that provides transparent and clear customer service.