Why are hoodies with zippers so hard to find?  

I thought you meant zipper hoodies based on the title. I was going to say you can find those anywhere. But yeah, zippered pockets on hoodies is not as common outside of Asian countries. I think this is down to weather and habits. I have found a few brands that offer them at Walmart though.

I think this is just a trend. I remember there being a lot of these in the early 2000's. I am guessing they will make a come back. I can't say it is something I ever went out of my way to find though. 

I did a few searches and found tons of options but They seem to be cheap Chinese brands. Well, Chinese-made, and unbranded. I know there are options for women's hoodies that have zipper pockets but it is not as common for men's. 

I see them online all the time. I think it depends on where you shop and if you are okay with off-label or imports. Check eBay and Amazon. I see them on there.