I'm not sure what exactly GP is referencing, but maybe it's the rare cases when the weakened virus in OPV mutates and someone excretes infectious, vaccine-derived poliovirus. I still don't see how that's the fault of the vaccine providers, since it's due to mutation and not a mistake in production of the vaccine, and OPV is a reasonable thing to use and certainly better than doing nothing.

In recent decades, infection from vaccines based on the live virus, instead of the killed virus, has been a primary source of outbreaks. The usual mechanism: Someone who was never vaccinated changes the diaper of a child who has gotten the live vaccine, gets exposed, gets sick.

Many years ago on Sixty Minutes, an elderly man who changed the diaper for his grandchild caught it and diagnosis and treatment was delayed because the doctor literally said something like "Decades ago, I would say this was polio. You have all the symptoms." and didn't consider that was possible because "we've eradicated it."