In Europe, it's mostly transfer and/or changing club at the end of the contract.
Right. Since all sports leagues have contracts, many trades are made due to contract reasons. BB doesn't have contracts, so trades have to be for the reasons that managers currently sell players for in BB.
The first reason I can see for anyone to sell players in BB using the TL is for cost reasons. I get rid of player X because my team is going to lose money if I keep him. So, it's because I have to make room on my roster for a cheaper player. My idea addresses this since you can only trade for a player whose salary is less than the player you are selling. Because I also added a minimum salary of 75% (or whatever the BBs decide) of the selling manager's player, you are getting trades of players that are similar in cost. One gets a slightly better player, the other gets a slight worse player and some cash which helps their economy. Both teams benefit.
The second reason I can see for anyone to sell a player is because they trained a great player and want to make money off of that player. Under my proposal, they can still do that because the selling manager can put the player up without the option for trades. Then, it is cash only. If they put that player up with the option for trades, they could also accept a player that is similar in value and some cash. Or just look at the offers, reject them all, and still accept a boatload of cash. Either way, both teams benefit.
The last reason I can see for anyone to sell a player is to shake the team up and try something new. With my trade idea, they get offers from other players and can find something different that might get them further along in the idea they are working towards.
Here is an example of the last reason. Say a manager changes his team name to the Gotham Dark Knights. He only wants players who have the word "Dark" somewhere in their name. He can offer up his players on the TL with trades enable and in his advertisement say that he will only accept trades for players with "Dark" in their name. He is much more likely to be able to build the team he wants if he can trade for these players than he is if he has to use the TL to find the players, make bids, and buy them. He is also much more likely to get players that won't make his team much better or worse because he is getting back similar value in the trade for the players he is giving up. So, his team is still competitive and he gets the team he wants. Everyone benefits.
even a thought out idea can not work in BB
That could be true. If anyone actually addressed the points of my idea, I would agree. But, instead, I am being told that if I don't like the poor arguments that have been made against my proposal, I should "leave the game".
I don't come in here just to argue. I am curious if there is any support from any players in the game for a logical, thought out trade option. It seems like a lot of new players ask for it. I am also curious if the BB developers think it could work since it uses their excellent existing work as a jumping off point for a fun game improvement. Lastly, I am curious if their are any flaws in MY proposal, not the one's people seem to be making up in their heads.