Some points:
Firstly, the master server and GLS are hosted on a server jits pays $$$ to keep running at ThePlanet.com - that's why you see stuff going there.
Secondly, the EULA is legally binding - that's why you have to check the box saying you agree before you can install.
Thirdly, to "scan your files" jitspoe would need to check the hashes of hundreds of files against a long list of cheats he'd have to maintain. This simply isn't practical. Currently, the cheat detection scans a changing subset of texture files to make sure they haven't been modified as checking all of them would simply take too long and eat CPU like crazy. Extending this to other files than those related to digitalpaintball would be insane. However, if you had hacks for another game loaded in memory, they might be detected.