When Can It Be Waxed?

I think they use ovens to cure the paint. And probably robots do most of the painting if not all, so less mistakes. Plus chemistry has changed.
No idea what the dealer said in the 60's about waxing. Probably sure do whatever you want
Unfortunately the quality of paint on newer vehicles has declined significantly. There are more paint defects in new cars than I get in a body shop environment. I typically paint 1-2 brand new cars per week repairing factory defects. I think the factories have realized it's cheaper to pay us warranty to fix them than to pay the factory employees to correct these issues at the factory.