Questionable touchdown in the Raiders vs Chargers game?

I thought is was a TD. That call is to subjective when it come to possesion. Does he have control the second his 2nd foot touched down or is it 2 seconds later 3 seconds. There is too much room for human error the way the rule is written. Ecpecially since it was called a TD on the field i just don't see how they could over turn the call. I like that they changed the rule about if someone caught the ball in the air and was pushed out of bounds they may or not have ruled him in bounds, again to subjective. Now even if he is pushed out of bounds in the air it is an incomplete p. There is no room for error. Why can't they do the same for this call in the endzone?