Oven temperature scales.

Having used both gas and electric cookers, I am puzzled as to why electric oven thermostats are always calibrated in degrees celsius and/or farenheit but gas ovens thermostats are calibrated 1 to 10. Is this a legacy of old and different designs or is there an important reason.

I know it doesn’t take much to convert a temperature to the equivalent gas mark, but wouldn’t it make things (labels, recipes etc.) simpler if a universal standard was adopted?

Not exactly a life or death matter, but I was just wondering.

Every gas or electric oven I’ve seen (United States) has degrees farenheit. Possibly the 1-10 scale is from older ovens?

My gas oven (circa early 60s by the look of it, I rent) has temperature degrees, not just 1-10. I know my aunt (only other person I know of who has a gas stove) also has degrees for hers.