Business time means no personal time (when traveling)

I know I mentioned this before, but business trips in Korea versus the US are different. Koreans have STRICT rules, and they just don't bend them. If you want to leave a day early on a trip (say Saturday instead of Sunday), good luck. Trying and take a vacation over a business trip? Good luck. And all of this makes you wonder, what do they really do on business trips in Korea? (And why are the rules so strict, how badly have they been bent before?) Is it lack of trust, or have people done something to lose the trust? (I am not going to answer that).