My wife wasn’t allowed onto the plane until she covered up. Is this normal?

Throwaway, just in case. I have talked to my wife about posting this but she isn’t comfortable, and it was her experience.<br><br>So last weekend, my wife was flying solo (no pun intended) out of Toronto. She is flying to San Francisco and wears her usual plane clothes, a t-shirt and leggings. For reference the weather that day in Toronto was 25c (77f) so it was pretty hot outside, and I find leggings to be a comfortable way to travel. Anyways, she doesn’t have any bags to check, walk in, go straight to security, everything is normal. She gets to the gate, and when she tries to present her boarding pass to the person scanning it at the gate, she’s not allowed on. She’s told she needs to cover up because of her attire, and pointed towards a kiosk that sells floral shirts that would cover her up.<br><br>I’m not describing her outfit out because someone in her story was going to. She says a lady walked by and said “I don’t understand why you’re dressed like that when you’re inside. Don’t you know you’re cold?” So my wife explained to her that back home it was 25c, and in Canadian culture it’s pretty common to see people walking around in t shirts and shorts when it’s 25 degrees out. The lady replied “well you shouldn’t be dressed like that, it’s so skimpy. You’re going to be cold on the plane”. So my wife explained to her, “I’ve been told I need to cover up” to which the lady responded with “oh thank goodness. That’s so skimpy, you need to cover your body”. Anyways, my wife covers up, and is let on the plane.<br><br>So my question is, how common is this? Is it normal for people to be denied boarding because of their outfit? Would I have been denied too? (I travel exclusively in shorts and a button down).<br><br>&#x200B;<br><br>(edit) Some people are asking about the airline, it was Air Canada, and the flight was to SFO