Nah, this doesn't quite fit into the "people on such and such server are mean" category, but a more general question. As Death On Ice said, server owners can do whatever they like. Some of them are nicer than others, some of them are not.
It's quite possible that the two servers you tried to join were either bad places to go, or filled with idiots (some people now and then like to think that because they're playing on a server, no matter where it is, they're "entitled" to kick whomever joins so they can keep their private game. On the servers where I'm an admin we usually permanently ban those kinds of idiots, since it's not their server to make that kind of call).
My suggestion would be to try whatever servers you can where your ping is low; if you want to say your location, others may be able to suggest good places to go (For example, any of the PureTremulous servers which are located in the US, but some folks overseas have had good connections there as well).
Anyone can setup a server, and anyone can be an admin on a server, but not necessarily everyone *should* :>
