"What incentives do you have to keep putting in any effort? Doesn't this lead to massive amount of corporate theft? In the US you are typically "shown the door" when your employment is terminated to minimize the possibility of disgruntled ex-employees taking corporate IP with them."

The incentives to keep doing a good job are your intrinsic motivation to do a decent job, your professional reputation and receiving good references for your upcoming job applications. Doesn't the american approach of showing employees the door right after being fired to a poor transfer of their responsibilities?