There are definitely a good number of small businesses around me (cafes, and similar places) that offer a cash discount. They don't have a sign offering it, but when I pull out cash, they revise the price down.

More and more small places around here are explicitly offering the discount either with a “3% less if you pay cash” but more commonly now a “listed prices are cash or debit, credit pays more”.

It’s a noticeable fee for them.

It is against VISA ToS. Small businesses can risk it but large businesses would get sued and VISA would refuse to do business with them

Nope, not against VISA ToS. Post you're replying to indicates it's no longer "illegal" but it was never actually illegal to charge a surcharge, it was just disallowed by ToS. This is no longer the case as of 2013 and retailers are now free to charge a surcharge if they so choose.

You are referring to the USA here. In most parts of Europe / EU it's actually still illegal for vendors to discriminate on price based on the type of payment.

It's newly illegal, and even that's only since the interchange fees were capped by the European Commission to a maximum of 0.3%/0.2%.

As far as I know they're also allowed to charge surcharges for non-capped cards (e.g. business/commercial cards, three-party schemes like Amex etc.)