For small companies, the cost of having to declare income in multiple jurisdictions is a nightmare. For big ones, it's a rounding error. Why not declare that the single market rule of paying tax in a single country does not apply to global corporations controlling subsidiaries in most countries? Seems to me simpler than inventing a tax on turnover.
If it makes it more difficult for mega corporations to compete with local businesses: well, that's just icing on the cake.