Because no one watches non-revenue sports and they cannot survive without being almost completely funded by revenue sports, which do have these transfer rules.
Revenue sports such as football have to care about whether transfer rules have an impact on whether fans watch, what they do to overall parity, etc., because they need to generate revenue to survive. Non-revenue sports don't need to worry about that, because they depend solely on people watching football (and basketball, to a lesser extent) to survive.
Agreed the business model for CFB is pretty messed up. I guess that's what happens when on the one hand you are saying that it is an amateur sport so you can't treat players like employees and on the other hand USC is paying Lincoln Riley $15 million/year to abandon Oklahoma's players.