PALs can often be either copied (readback and programmed), or they are simple enough usually to create a workalike. A PAL16V8 (very common) only has 8 latches, so it's usually possible to create something that behaves identically as you can only fit usually a small state machine on them at best. It's possible it's only used to do something like number what car you have or something silly like that.
PICs and other microcontrollers, however, can be locked down to where copying them is just about impossible. Many many games used a locked PIC as the basis of their copy protection, though recent development have allowed about a 50% success rate of unlocking those older PICs for program readback (the other 50% of the time you tend to destroy the chip).