Visible symptoms aren't the only concern, you can be contagious without symptoms, and there are studies showing that 50% of all infections could be asymptomatic - https://eurosurveillance.org/content/10.2807/1560-7917.ES.20...
I was precisely stating the reasoning behind the number we see everywhere. I was not offering an opinion on whether that reasoning is sufficient to prevent the spread of COVID-19.
That said, in an emergency it makes sense to focus on people with symptoms and tell everyone else to act like they might be exposed. In which case people who have been exposed and have symptoms should act like you want everyone else to act. Which means that if they are working in a warehouse, you want them to have protective gear to prevent them from giving it to people.
Which is exactly one of the things that this strike was about.
The 2 weeks figure is because we're reasonably confident that if you haven't turned up with symptoms in 2 weeks, you aren't going to.