A recent commercial for the commission-free trading app Robinhood shows a store's stockboy noticing features about the company, such as if shelves were empty/full of product, and then trading on that information. I've only ever heard of insider trading in relation to white collar employees, or at least those with a specific piece of material non-public information, as opposed to general knowledge of day-to-day business trends. I presume knowledge about shelves where shoppers can go would not be insider information because any member of the public could go there, but what about info gleaned from the back room or any non-public areas?
I don't think the commercial describes insider trading. For a large corporation, the amount of inventory on the shelves in the stockroom in one location isn't insider information. It tells you nothing about the overall health and plans of the company, but it might tell you something about that one location.
Having an advanced copy of the monthly inventory numbers for the entire corporation before they are released would be insider information. Having access to the plans for the coming year would be insider information.
The commercial (as described) is nothing more than the portrayal the advice that you should invest in the sectors/companies you know. The idea is that things you observe in your daily life can allow you to spot a trend.
That stock boy may have noticed that product X is now selling quickly, which could mean that manufacturer Y has a product about to go viral, so they will decide to invest in the manufacturer. That isn't insider information; they are just making a guess based on a single data point. They don't have access to the sales for the manufacturer nor do they have any connection to the manufacturer, but they are investing based on the sector they know.