Even with the switch on the wall nothing is certain. See my sibling post to parent. We had a wall thermostat but all it did was send a trigger current. If the thermo pile wasn't generating enough current nothing would happen :)

Sooo many different systems and many are just not well thought out. Especially in climates where it usually doesn't matter.

Here in Quebec it does matter so the one we have works in all conditions with various levels of manual intervention. We don't even have the one with a battery operated fan but even that exists.