That's a great question, and one I wondered myself before buying one. After using a sensor bin for over a year, I can say they genuinely work well, but with some important caveats.
The main benefit is hands-free hygiene. When your hands are messy from cooking, a wave of your hand opens the lid. It's incredibly convenient and reduces cross-contamination. The automatic closing is also nice, sealing odors inside effectively, especially if you use good liner bags.
However, they're not magic. The sensor can be finicky—sometimes it doesn't trigger if your hand isn't in the exact spot, or it might open accidentally if you walk by too closely. They require batteries or charging, so you have to remember to maintain that. Also, the mechanisms can be more prone to failure than a simple, manual bin.
For a busy kitchen, especially during food prep, the hygiene and convenience are real advantages. But if you're on a tight budget or prefer absolute simplicity, a good manual pedal bin might serve you just as well. It's a useful tool, not a gimmick, but it's best for those who value the specific benefits it offers.