Masks for Aug 19 baby?

I want opinions on this.

I had to take my 20 month old to the grocery store with me earlier this week and they refused to let me enter because she wasn’t wearing a mask, and they also wanted her to have hands washed with hand sanitizer.

Our province made masks mandatory for anyone over 2, she isn’t 2 yet so I told them that and they still refused. She would be sitting in the cart not touching anything so I told them that we washed hands at home and will not have her use their stuff, because she will most definitely put her hands in her mouth at some point.

I left and went to another store and had no problems at all. Should a child this young follow the rules as well?