Scaling Cost of Living

I was looking at Cost of Living in the book and noticed it doesn't scale with TL. That seems odd to me, as the higher in TL you go there are more luxuries that are considered standard living and should increase the cost of living. For example, higher TLs have electricity, so all but the poorest of people would have to pay an elecric bill where as in earlier TLs you don't have electricity (obviously) so there's no bill to pay. I'm not trying to calculate how much someone would have to pay each month for electricity, but I would think that should be part of Cost of Living. So, can anyone tell me why Cost of Living doesn't scale with TL?

Scaling Cost of Living