It's commonplace nowadays to buy bottles and jars of stuff from the grocery store and find a seal attached to the top of the bottle underneath a screw-on top.
Now, it's annoying to have to remove the spout from the jar, remove the seal an reattach the spout the first time you use it (as opposed to removing, say, a shrink-wrap plastic wrapper around the spout/cap). But you can sort of understand it. The seal is like the lid of a canning jar - it's a hermetic seal that preserves the contents from spoilage.
The trend sort of started with the Tylenol poisoning scares in the 1980s, and what became a seal against spoilage gained a second purpose as a protection against product tampering.
But the concept falls really, really flat when the product being protected is DISHWASHER DETERGENT!!!!