How come there isn't a really easy way to use portable apps for Linux? With Windows I can stick them on a USB flash drive.
This is a rampant disadvantage of "Linux". Worst than all, the cheerleaders will surely come to this thread with trolling talk about live distros, as if live distros and portable apps were the same thing - they aren't.
The simple reason is, apps aren't statically compiled. You can do that - they will increase in size. And then you will end up with Windows size installs and such. You can create portable apps easily: ldd <binary> Copy all listed shared libs + binary to some folder. export LD_LIBRARY_PATH=some folder. Run binary from said folder. Portable. Mrk