Don't know why you're being downvoted: Google had immense bargaining power with Visa (and the others). It might be a stretch to say they aren't paying 2%, but it's unlikely they're paying 3-5% + $0.30 flat per transaction (typical fees for small merchants going through a merchant bank payment processor, PayPal, etc.)
They certainly won’t be paying less than interchange though which in my world averages 2.35%
Interchange fees in Europe are capped to 1.15% online and 0.2% on payment terminals, and I'm sure Google, Amazon, and other big companies are able to negociate better fees
I doubt they have any negotiating power. Negotiations are always based on leverage, and second-best option. They have none of those. What can they theaten? To not take Visa or Mastercard in the Play Store? That they'll only take checks my mail?
They can sell prepaid cards, like their gift cards. However it's not as convenient.
They can start their own currency, but only facebook is going that way and it takes a long time.
There are a lot of credit cards that offer cashback rates between 1-2%. I'm certain Visa is not eating that so Google (and other merchants) must be paying.
Most credit card companies also get paid a lot of money in interest, it’s not like they rely solely on interchange fees for rewards programs.
Yes, you shouldn’t float a balance on your card - but the average person often does.