This issue has been discussed several times. The bottom line is that the size of the P2O market is WAY TOO SMALL to interest any big oil company.
The total amount of oil made into plastic is just under 10%.
The amount of plastic recovered is less than 10% of that. If you do the math and assume that 10% of the plastic produced was recovered and run through a P2O processor that amount of fuel produced would be less than 1% of the oil consumption.
Big Oil is not interested in a process that will produce less than 1% when it is in full nationwide production.