Because we have anti-fraud consumer potection rules and CCs operate on a make money first type of bais. The debit networks on the otherhand are a different story.
Yes, because we don't want these stupid locked down apps. Credit cards give buyers many protections, it's very easy to dispute an illegitimate transaction.
The consumer does not typically pay this directly. It may be passed onto the consumer indirectly through higher prices, but those apply to anyone regardless of payment method. On the contrary, I get cash back on purchases and other rewards.