I have actually thought about this before, as I used to design plumbing. The reason why we have toilets with the flushing mechanism at the top is because it is far more efficient to do it this way (consider how the toilet works). That is not to say that it isn’t possible to do; some toilets are made with a foot pedal, but it is not that common. It is likely much cheaper to make toilets as they do since there are less parts involved. Also, in public restrooms one has to consider ADA now and the pedal would need to be accessible.
I’m not averse to the foot pedal idea, but I think it needs to be refined. Another thing to consider is why they don’t install faucets that are operated by foot. It’s not that they aren’t made – they are installed in hospitals and laboratories all the time when it is important to have “hands free” operation. Again, I think it is more expensive to make these faucets and so they are not cost competitive. When I own my own house, I will definitely be installing a foot pedal operated kitchen sink, and perhaps a foot pedal operated shower (also made and installed in gyms now and then). I know I’d save a ton of water with these simple changes.
I don’t like motion sensors. They flush when they shouldn’t, they don’t flush when they should, sometimes they run constantly and never shut off, sometimes they don’t turn the faucet on…One day technology may improve reliability, but we are not there yet and should not be converting the entire industry of controls from manual to electrical. Besides, I’ve always wondered what happens when the power goes out. I think the pedals would accomplish all the same things in a much more robust way.