Earlier quoted context omitted.
Ideally you need nearby electrical and ability to get water to the washlet seat. Which is fairly easy/cheap in a bathroom remodel (which is what I did) but not necessarily easy/cheap otherwise. (There are simpler ways you can get part-way there as noted in this thread.)
...why would you need electricity for a seat with water?
I'm not sure electricity is required for basic operation but at least most models are designed to be plugged in.