Actually the problem has existed for many many years.
Todays pump fuels do tend to have higher loss in the lower temperatures of the distilation curve. Howerver the evaporation rates are still regulated both federally and also by many states. Generally RVP is the basis for regulating evaporation, but some places also use 'drivability'.
Any of several reasons for difficult hot restart could relate to fuel and temperatures.
One is the evaporation off of the intake's walls. When the walls are 'dry' on a hot intake then it will take a little longer to get started.
Another is some fuel loss in the bowl but this should be fairly minor. However what is lost,
if the bowls got hot, would be the lightest portions of the fuel - then its like trying to build a fire without tinder.
There also may be overfilled bowls. This was a problem with heat on the fuel lines between the pump and the carb.
Finally, any CAP and subsequent emmissions reduction packages ran retarded timing, leaner mixes at idle which had a side effect of increasing hot start difficulties.
1963 Chrysler Master Tech on vapor in the feed line:
http://www.imperialclub.org/Repair/Lit/Master/188/Page13.htmChrysler Fuel pump bypass kit:
https://board.moparts.org/ubbthreads/ubbthreads.php/topics/2288216/tsb-for-fuel-pump-bypass-kit.html1973 Master Tech "Lets Get Them Started"
http://www.imperialclub.org/Repair/Lit/Master/307/index.htmand the film version:
http://www.imperialclub.org/Repair/Lit/Films/307/Examples of fuel distilation curves:
https://www.forabodiesonly.com/mopar/threads/hot-fuel-lines.438352/#post-1972557913More links about Gasoline:
https://www.forabodiesonly.com/mopa...gular-vs-premium.425033/#post-1972367213
