We basically need to increase the cost of plastic to account for all externalities.

It's a super material, it needs to cost as much as competing natural materials: nylon - silk, whatever plastic bottles are made of - glass/aluminum, whatever packaging is made of - paper/textiles, whatever containers are made of - wood/steel/aluminum/etc. Similar story for paints.

Basically, excises, but for plastic instead of just alcohol and tobacco.

We do this, plastic starts being used just where it really makes sense.