(I have very limited experience in Mainframe systems to take my comment with a grain of salt)

The problem as I see it is IBM wants to have its cake and eat it too. Typically a Mainframe is leased and then setup onsite. Under this model, it would seem that you would get unlimited use out of it because you’re paying for the power, and it’s literally on site. However by charging per CPU usage, even though you’re using it on site, you still treat it as a “cloud” appliance in terms of pricing

If I spin up something in AWS for example, it’s metered yes but that comes to be at the benefit of not having the machine on site and therefore not having to worry about it’s power, upkeep, etc.

It would be like a car company selling you a car and then charging you to drive it per mile.

Well isn't that because most IBM customers don't actually pay upfront for their mainframes, but instead effectively lease them? Car companies DO charge you per mile to drive a leased car beyond the standard allotment.

I think your comparing apples to oranges here.

A CPU doesn't have wear and tear like a car does.

Though, it does have a useful lifespan which is more or less equivalent to wear in an economic sense.

The difference here is that 'the cloud' like you mention is generalised across an industry of various companies. There may be some pain points moving between vendors but it can be done. Good luck trying to move off that mainframe.