“It’s a gentleman’s agreement at best, and a cartel at worst. Either way, no business is going to start an ‘undercut war’ because they don’t want their opponents to do the same thing.”
Play any MMO and you’ll see the fallout from that. When it doesn’t actually matter in the real world and people go do that everything plummets in value to near 0 and makes it not even worth your time to attempt even in a damn video game. They’ll never drop prices to compete in reality because of that reality.