So zinc is cheaper, at 2 dollars a pound, instead of 18 dollars a pound for the pewter. On top of that, it looks nicer. It took a while to figure out how to melt, because of the higher temperature, but we now know how to melt it.
Here’s a comparison. The circle on the right is pewter. The blob on the left is zinc. As you can see, the zinc is a lot cleaner and better looking.