> Now how high would that tax need to be to so that everyday goods would dump plastic? And what would that mean for other uses of petroleum?

Charge what it costs to clean up, and spend the tax on cleaning it up.

> The problem is that not every use is equal, some are more necessary than others

That's exactly why the price mechanism works - the necessary uses will continue to happen even at a higher price, while the frivolous ones will stop.