Hello friend.
You misunderstood the "TEST" word

Let me make this word clear for you and for whom thinking like you.
If a player fully suitable for this job (Game Master) then he/she gets TEST Game Master tag first. What is this? Administrator, Head Game Master, Game Masters and also community testing that guy. Test Game Master learning his/hers job, his/hers responsibilities. For example, he/she learning how to Close thread, How to open; How to Host an Event; How to ban someone; Sharing his useful opinions in Report Section; Learning banning procedures and if he/she learned his/hers job, he/she passing the TEST Period. Thats the meaning of Test period.
Now let's check for another variant and a variant what you wanted, suggested.
What will be happen, if everyone, at least 50% of players could be applied and got TesT Game Master tag:
1) He/she will shares his/hers Credits and will made unbalance in the server. It will be hard to fix this problem.
2) He/she will bans everyone who he/she dislike.
3) He/she will share his random opinion in Report section then it will make big confusing between Game Masters and their brains will be mixed.
4) He/she will talk with Players in rude ways and will make them don`t enjoy from the server and leave the server.
These 4 are the most important ones. Of course after doing these things they will be demoted and will be banned by I.P

But does it matter? Damage will be done
That's what will be happen if we take everyone as TGM. We have to know players before giving them TGM position. We have to trust them. They must be mature, responsible, active, well-known, helpful, friendly, kindly and so on.