Stealing signs in high school baseball wasn't a huge deal. You watched what the coaches did and you could figure it out from the field and or dugout. This had been going on in the Majors going back to the early 1900s. Now these douchebags in the Majors have cameras all over their home ballparks, banging trash cans, etc.
It's become more prevalent with football as the game has changed. More passing, more sophistication with offense, so the plays are called in from the sidelines. We could often figure out from the press box what calls were coming in from the sideline. Again, not the end of the world. We did our best to change things up on our end in order to not have tendencies.
There is a very obvious difference when it comes to stealing signs from the sideline, field or press box in a football game versus the network of sophisticated fuckery Michigan had going on with this Stalions goof.
They all knew about it and frankly I'd be surprised that "everyone" had/has systems like what Michigan had been doing.