That, what you described about the cost, is exactly what started my layoff. I learned to fly in the early 90's in Willimasburg VA...think my PPL cost in the $3,000 ballpark. Can't remember for sure, but I think the 150's and 152's rented for around about $35 wet, the 172 was around $45 wet I think. By the late 90's I was in Atlanta and was paying more than that to rent, but not much... I want to say the 172's were maybe $60-ish, which seems about right trending inflation. Then I moved and only just a couple years later 1 hour rental ate up most of a $100 bill. The higher performance stuff was of course more. They were typical rentals, not well maintained, availability would be hit and miss, etc... It was costing too much for what I was getting. I decided that the only way it makes sense for me to keep flying is to finally buy something.... so I hatched a plan...but then before I did I got laid off, eventually had kids, etc...
Anyway, something happened because the rental rates went up more than the inflation calculators say...so i don't think it's just the value of a dollar. Your $12 in 1970 calculates to be about $40 in 1990..... which is close to what I was paying. The $45 I was paying in 1990 for the 172 should be ballpark $100 today it seems, but around here an equivalent 172 rents for $165...and it's a lot more worn and tired than they were back then...really in pretty bad shape now.
Even though a lot of those things you miss don't exist any more, things are pretty cool now with the ipad and GPS, situational awareness, weather information in the cockpit, etc... are light years better. Some things I do not think are better at all, but overall it probably is.
My suggestion...if you haven't already started. Go to the local flight school and hire an instructor for a discovery flight. That's what I did. Told him I didn't want to consider this a hardcore make-me-work for it first lesson. He handled the radios and such and we did what amounted to just a fun easy flight. It was great to get back up there!