A small business is low volume, hence going to have a hard time getting good rates. And they're also constrainted on resources, so the extra effort to get a few points off may cost more than those points (as written above – they're low volume. The cash value for a bp is much lower for them than for a high volume business)
No doubt, you can get ~2% processing and no flat fee even with low volume but what you get isn't as polished as Stripe and takes some more development work to integrate/use.
