Most Helpful Guy
This is two different questions but I can help you with both:
1. You can tell how much he likes you by how much time and attention he spends on you after he's gotten what he wants. If he still wants to hang out and spend time with you when sex is no longer and issue, he likes you as a person and sees you as more than an easy fuck. If he just bolts and then doesn't hit you up again until he's horny you're a booty call.
2. Cause we like having sex but if we say "Hey let me borrow your vagina real quick" it doesn't work out in our favor.