That was normal in Texas ~15-20yrs ago. But in the intervening time, I've seen that become less common. I've run into places that won't let you pay after and will instead just ask you to prepay (full transaction) and come back in to get the difference refunded.
But I've also ran into plenty of places that if you hit "pay inside" on the pump will simply just turn the pump on, or will call you via the pump intercom (is that common everywhere?) and tell you they're turning the pump on for a max of XX gallons and to prepay or use the card at the pump if that's not enough.
The pump intercom is done because then you know someone inside actually saw you and is expecting you. If you drive off without paying they are much more likely to notice and call the police in time for the police to catch you. Or at least that is what they want you to think.
Yeah, I figured the intercom call was to get you thinking that they're watching closely, even though they're usually too busy with other customers to really be watching someone on the chance they drive off.
But I've also ran into plenty of places that if you hit "pay inside" on the pump will simply just turn the pump on, or will call you via the pump intercom (is that common everywhere?) and tell you they're turning the pump on for a max of XX gallons and to prepay or use the card at the pump if that's not enough.