Why players who started at this server can’t transfer teams to NA or SA server ?!
Because you lack nuclear warheads you could threat IMC with. There’s no logic you could use to convince them in this case 
Because NA servers were the first ones online.
The US to EU/SEA transfer is for those EU/SEA players who had nowhere else to go when the game launched.
And they said that unless you want to play on EU or SEA you should not start playing on it.
You can only transfer from older to newer, the transfer that took place was because people had started playing before IMC were certain about having regional servers. they became available roughly as so.
Early access launch:
Klaipeda
Orsha
4 Hours post launch:
[EU]Fedimian
1 Day post launch:
[SEA]Telsiai