Totally agree with your points.

On the other extreme, (and due to my personal interest in practicing knife sharpening), I ended up using a pocket knife and a couple quality sharpening stones as my “razor”. Too lazy to calculate whether the long term cost is worth it, but the setup will probably last me a lifetime. If avoiding waste is really the highest priority (over convenience) then I would argue that sharpening your own razor blade is the only rational way to shave.