> double clicking is extremely uncommon on the web so that would be a big red flag.

You've never had a slow internet connection have you? I've seen double clicking from all users in the office. Comes from frustration.

How many times have you tried to open an application; for it not open? So you click the icon again only for two windows to split open?

Young, old, even techs. It's not as uncommon as you think.