You kid, but in some places that's already in the process of happening. See Sweden, for instance.

https://www.bbc.com/news/business-41095004

Yes, it is unfortunately already the case in most EU countries. In France and Italy, for example, you can't buy a new car cash (cash transactions over 2.5K euros are basically illegal).

This is a very profound loss of individual freedom, almost as important as losing right to free speech would be, yet strictly no one on the political spectrum seems the least concerned about it.

There is likely a balance here, somewhere.

Be careful equating money with free speech.

Citizens United in the US has had equally-troublesome consequences, based on the premises that corporations are people and money is their speech.

Conflict of interest plays a role here, and that's unfortunately something that has been under constant 'redefinition', especially in the last 20-40 years.

They're trying to do that in India right now.