Which expenses would that be that are genuinely avoided while maintaining feature parity, rather than merely avoiding the feature that is bought by those expenses in the traditional system?

For example: Of course not having to worry about chargebacks and related fraud makes Bitcoin potentially cheaper than the existing credit card system. On the other hand, fraud protection is a useful feature, and adding it on top of Bitcoin removes any cost advantage that Bitcoin might have started out with.

This example provides a template that, as far as I can see, applies to every so-called cost saving aspect of Bitcoin (except possibly the fact that Bitcoin might make the whole banking system more competitive; that would undoubtedly be a good thing).