We are still suffering a Supercharger drought here in northern Montana. The northern east/west highway in MT has a 400 mile stretch with no chargers while they are building out the Interstate corridor in the southern half, with plans for a charger every 50 miles. I expect it will be another couple years before US #2 starts to see some superchargers. Politics in action!!!!
Charging fees vary quite a bit but the non-Teslas are paying more than 50 cents / Kwh if they don't pay for a membership. For Tesla owners, the fees are from 21 to 40 cents. When the opening of the Tesla network to other EVs was first announced, the hand wringers were convinced that the Rivians and Lightnings would crowd out Teslas, at the chargers. Realistically, there are just not enough of the other makes to make any difference. I charged at a few sites that allowed non-Teslas to use them if they happened to have the NACS adapter. I saw none charging on my way home. 
Juice for this trip and a couple more that I plan this year had no cost because someone bought a new Tesla and used my referral code.