n my country the lowest team even has a sponsor who is paying the salaries of the lower level.
That does not mean that is like that everywhere. Remember this is a global game.
Whatever you said about coaches is a blur. Coaches salary raises are needed to keep staff transfer active. There was a system before that lowered the coaches level during his stay at the club, but current version is better. With no salary increase, all you have to do is buy a lvl7 coach and keep him forever.
As a friendly match to derive revenue from it. 10 fans attending the game, or 100, it's a small income
Ever heard of arena costs? Rent, electricity etc. What if a team does not want to arrange a scrimmage. Scrimmages are ment for training purposes (and GS maintaining) only. It's not ment for making extra cash. Want some more cash, stay in cup. Some of the things in BB are optimized to suit the game. Going for realism in everything, will just ruin this game completely.