The hinges break. The silicone ones don't have any.

Yes, collapsible lunch boxes exist, but skip the plastic-hinge models and get a silicone one if you want it to survive a year of daily use.

The fold-flat containers with actual hinges are the trouble. You know the ones—plastic base, side panels that fold up and lock, like the generic “collapsible” microwave containers. The hinge is the weak point. After a few months of opening, closing, and dishwasher heat, the plastic fatigues and cracks. Once the hinge goes, the box won’t hold its shape or seal, and it’s garbage.

One-piece silicone boxes (Stojo and a dozen cheap knockoffs) don’t have that problem because there’s no hinge. They just squish flat, and the crease flexes indefinitely. The tradeoff is that silicone can tear if you dig at it with a fork, and it holds onto tomato smells forever. It will eventually fail, but it’s a slow wear, not a sudden snap.

Rigid boxes are still the durability champs if you don’t care about storage space. But if the empty box sitting in your cabinet is the problem, go silicone and just accept that it’s not a forever purchase.

Rigid is for people with deep drawers. The rest of us fold.