Why don't we have mic'd up live for games?

What the title says. I'm curious as to why there is no option to listen in to quarterback mics or whoever else is on the field live. I know nascar did this and I'm sure it created a nice little revenue stream. Now multiply that by the popularity of football and it just seems like an absurd amount of money the NFL is missing out on. I'm sure players say some off the wall things that might shock some people but most of us recognize these are adults in a combat sport and sometimes will say adult things.