Do switches induce voltage spikes in the AC power grid?
Yes. My old washing machine used to inject nasty spikes into my mains. Does it affect ‘sensitive’ electronics? Yes. Most goods for sale in the western world are required to be compliant with a number of standards regarding putting nasty interference on the mains and being able to tolerate a number of common conditions encountered on the mains. So your ‘average’ whitegood, tv etc is designed to withstand such interference.
Devices like varistors are used to snub the arcing across switches and relays. Capacitors are used as well. The exact method depends on the problem you want to solve.