Relays are expensive and have limited lifetime. Choosing a proper relay for a particular application is also important. In other words relays require a bit more of everything when compared to a simple electric switch. So why not instead of using relays, manufacturers somehow couple a small servo to a simple electric switch. Then use it for switching, by controlling the servo. We too can do it (though not perfectly) . What's the reason that relays are so popular and so common for power switching? What's the flaw in using a switch as suggested?
Edit: Using switch can be a one time investment instead of using relays which requires replacement. Also, the cheapest servo motor(premade) can do the work for us. Main idea is lifetime, which I think, may be a reason enough! Also, if this setup is fabricated there may be less chances of individual part failures.