Usage based billing sounds like a nightmare though.
Taxes in the USA are a nightmare too. I have a friend that lives on a street, and for one side the tax rate is 7.5%, and the other side its 9.25%. Literally no company we tested got this right. Even Amazon.
I truly believe in usage-based billing, so I do think pricing are getting more and more complex over time.
Taxes are a nightmare for everyone also (in Europe too...)
My advice for anybody thinking of building their own subscription management system is to stop and go look at something like Zuora. You do NOT want to get stuck maintaining some home grown subscription management system--it will never be better than Zuora and you'll always be playing catchup, leaving your company unable to quickly react to the market. All the time spent adding functionality you can buy from a third party is money that you could have invested in your actual product. And worse, the fact you couldn't quickly react to the market because some key feature was missing in your homebrew thing is literally leaving money on the table.
That's really great that Ford uses Zuora. But for someone trying to work with an inhouse system that doesn't map to what a system like Zuora can handle... you now have technical work and a lot of political and non-technical work, and a lot of internal coordination to get all relevant people on board to commit to a change.