Some industries are very low margin while others are extremely high, I don't think this is viable without breaking a huge chunk of the economy.

Depends on how it is structured.

One way for example could be akin to a cash (and equivalents) tax on holding large amounts.

It would incentize spending the cash in r&d , acquisitions , dividends etc. Low margin companies will not be too badly affected

That's not a revenue tax anymore.

That just forces companies to minimize their cash stockpiles through investment, inventory, dividends, etc. How does that make the tax system fairer?

All those categories have already taxes associated with them

Expenses -( VAT/GST etc)

R&D/salaries - income tax for employees

Divendent - income and other taxes

Acquisitions/investments - seller pays capital gain tax etc

Disincentizing savings to boost the economy is not only applicable for regular people it also applies for companies.

Low interest rates are really today applicable for us. Companies with billions of dollars are getting enough returns to keep cash rather than spend it.

As other people have pointed low margin businesses like fintech would get skewered with this. For example, payment processing companies recognize the value of the transaction as revenue even though their cut is 1-2%.

You would shift the gaming of system from happening on the net income level to gaming of the system happening on the revenue level.

Most countries already levy VAT/sales tax. But almost everybody believes that those are all paid by consumers while corporate taxes are all paid by business owners (mental picture: Bezos/Gates/top hat wearing Monopoly dude, not poor old lady drawing on small pension).