I think the difference in the pricing is that they are shops that are "Night Eligible", meaning, of course, they can be performed at anytime, but, if done at night, you shall receive an additional $5 or $7. These shops are different than the shops that must be performed at night. Those were much more highly bonused ($10).
Would that seem correct?
Often, at the end of my shopping day (3pm or later), I pass gas stations that I will do the next day, but have decided not to since it is dark and there is no incentive to do so (and I just want to get home!).
I appreciate that these shops will pay more if it does become dark and I might just do them that very evening.