I agree, use of bad language - especially with younger kids is not the way to go. But honestly, I think many try to take to much of a "High Road" and have an unrealistic expectation that certain things should/or never will be said.
Point I'm trying to make is: If it's used and is to the point everyone think's it's OK or part of everyday use...the issue needs to be fixed.
But there are also many people who head hunt the 1st time someone says the wrong word in front of their kids. Whether we like it or not, our kids will hear this - and way more than many naive people imagine. There's some middle school discussions that make "Locker Room Talk/Break Room Talk" seem pretty mild...!
Remember: These are words, and 'words' only hurt to the extent how we take them, or use them in an inappropriate way.
Teach them that these should NOT be used, especially in every day conversation and their are bettter ways to communicate your message - and you'll look "smarter" in doing so.
To more directly respond to the OP... (this is coming from a former TB softball coach, but also a HS football official)
Most (HS football) coaches nowadays do try to watch it to some extent with language...but some still let it fly (a few alot, but that typically gets curtailed by the individual schools).
The football environment is much different than most other sports...its a sport played with controlled "Anger" that amping up your players is a huge part of the game. Certain words, and an over the edge delivery get the kids attention much differently...
Players and coaches in this sport do take language farther...I'd say if its too loud and open for the public to hear, the school will react and curtail it, but don't expect it to stop behind the scenes.
