Only because people are silly and started buying all they could find and hoarding it. Friday I ordered a case, 80 rolls, for my shop because we were low and it came today. I could have ordered more but don't want it taking up space. Any supply problems in the US up to now are from people buying more than they can use because they think it may be hard to get.
In my opinion, the easiest way to handle this is for the suppliers to raise prices when they see increased demand. This would stop the problem.
Except that can be illegal