The EPA did demand lower ZDDP levels in motor oil. They did not demand that it be eliminated altogether. Just reduced.
The REAL problem was that the cam companies switched to cheap-shiit Communist Chinese cam cores and lifter bodies, then blamed the resulting carnage on the oil so they didn't have to warranty all the defective junk lifters and cam cores they sold.
Reduced "zinc" (really, ZDDP) is nowhere near the problem the cam companies and hot-rod magazines made it out to be. But since that story made sense, and got published all over creation, oil companies started making "break in oil" at three times the profit margin. Now it's a self-perpetuating deal--and everyone but the consumer is rolling in money because of it.
