boredcounter, you wrote "On ONE side, who gives ATC the right to level cap"
Hmmmmmmmmmmm, that does seem to be a little cockeyed
"Level Capping" as such comes about, at the moment anyway, by the new enroute centre (Swanwick) not having enough staff (which was known by NATS Managementr BEFORE the centre opened - at least FIVE YEARS before I might add !!!) to man the centre properly.
Therefore airlines opt to fly at an initially lower level to get an "on time" departure - or if not "on time" at least to avoid excessive delays.
Ergo, "level capping".
And please note, we "dustbinmen" (
) will always do our UTMOST to initiate a climb as soon as possible.