[unbalancedevh]

I've very late to the discussion, but this seems relevant anyway -- The issue isn't just the cost of getting/retaining customers. Businesses don't charge solely based on cost, they charge based on what customers will pay. Existing customers also are willing to pay more to not have to move. If customers are willing to pay more, then it makes good business sense to charge them more. For the owner, having an empty apartment is the worst, so it's worth it to do extra work and give discounts just to get somebody renting.

It isn't nefarious, and you do your part by being willing to move instead of pay the higher price. It's all just the way the capitalist market works.