The problem with recycling/reusing plastics has been notoriously difficult in the past. That is why it's so often incinerated/dumped instead of reused/recycled.

I want to explain my view of this:

Reusing plastics is difficult because the bottles are often produced in a way that makes them as thin (and lightweight) as possible. That has the advantage of saving oil, but has the disadvantage that they are in turn so brittle that if you tried to reuse them, chances are high that the bottles would either break, or - more dangerously - abrasive effects would cause the bottle to get tiny cracks, which would set free microplastics and potentially additives, which could be really toxic; and nobody wants to be responsible for this, so they are dumped.

Then there is the problem with washing the bottles. A lot of the plastics is not made to be brought into contact with soap, as I understand it, because the soap severely impacts the plastics. So washing them thoroughly is difficult.

Recycling has a different problem. Recycling consumes more energy than simply producing new ones. In the past, that was the reason to dump them. With cheap solar energy, the game could change. Recycling still takes a lot of energy, but as energy is getting cheaper, industry could reuse the carbon atoms in the bottle; in other words: reuse the material that's in the bottle, not the energy that's in the bottle. This will require even cheaper energy prices though to be economical.