@Jay1549 I'm not sure what you mean by the service fee being "all over the place", but the Airbnb service is anywhere from 14-20%, and has nothing to do with hosts. What algorithm Airbnb uses to determine the % of fee they charge isn't something they make known.
As far as the cleaning fee, it can't be standardized, because the hourly rate for cleaning services varies significantly throughout the world and even in different areas throughout a country. It might cost an American host in Chicago $150 to get a 3 bedroom house cleaned, and the same size place in Mexico might cost $25 because wages are so much lower.
The reason the cleaning fee can't just be added into the nightly fee so you see it as one charge is because it's a one-time fee for each booking. If you stay for 2 weeks, you pay the same cleaning fee as if you stayed for 2 nights, because the place just gets cleaned once per booking, not like a hotel with daily maid service.
And what many guests don't realize is that the same cleaning has to be done whether someone stays for 1 night or 10- the accommodation has to be presented to each guest at the same standard of cleanliness. And some guests manage to make a huge mess in 24 hours, while others leave it in good shape after 2 weeks. So hosts have to average that out.
And some listings have no cleaning fee at all, mine doesn't.