My assumptions are based in that I’ve worked in the industry. There’s plenty of small restaurants that are cash only, because they operate on the thinnest of margins. Gas stations as well. To the merchant, a fee of 3% + .10c per transaction is very common. More for Amex.

The second point sounds like an economics 101 conclusion. Network effects are real. Regulatory capture is real. Starting a new card network is harder than beating google in ad revenue in search.