Pilot lights were common on gas powered appliances in the past, but aren’t very common any more due to a few major reasons. A pilot light is constantly being fed by gas to keep it burning, which in itself is a waste. While it might not be a lot of gas being used, the pilot light burns 24 hours a day, day in and day out, which actually adds up to quite a significant amount of waste.
There are also safety concerns when it comes to pilot lights. Why is that? If a pilot light goes out for some reason, there should be a safeguard that turns off the gas, but this is not always reliable, especially on older appliances. If the gas isn’t shut off, there is a major risk for an explosion once the pilot light is reignited.
If you have to reignite a pilot light, you should first make sure that there isn’t a buildup of gas. If necessary, you should vent the area well before trying to ignite the pilot light.