I had a feeling someone would say that about scissors.

However, scissors have been around for a VERY long time, and therefore would be a reasonable tool to plan for the consumer to use for opening packaging. However, I personally find these titanium plastic containers to be quite difficult to open sometimes even with scissors due to their thickness, and also how sharp they are once cut.
Cans are also practical, because they keep food fresh for a long time.
These kind of insane boxes/plastic are not practical in any way. They produce more waste, make products more difficult to open, and only serve store owners and not consumers.
OK, so now maybe you found a cheap solution for CURRENT shipping materials. What happens if nobody complains, and then you have to then buy ANOTHER cheap tool for opening your PURCHASED items when they develop some other packaging material?
Easy suggestion: the stores who are concerned about package tampering develop their own containers which can be opened at the cashier when the item is sold. I have seen these in stores such as Best Buy, and it works very well.
there is no reason manufacturers have to be involved in this step.