When I was in Australia I had trouble understanding some of the locals. I had to listen real hard. Now those on television spoke pretty much like I would expect living in Southern California.
One of the hardest times I had understanding “English” was when I was in Hong Kong in the late 60’s. The spoke with and “English” accent with a “Chinese” accent thrown in for good measure. Say what? Hahaha.
Here in SoCal I use a lot of those terms back and forth such as pee-khan and pee-can. Same with soda, pop, Coke or soda-pop. Same with some of the others. I guess it is just how I feel that day.
An awful lot of people moved to California from the rest of the country after WWII. I'm guessing they brought their own regional variants with them so there'd be more leeway there than in other parts of the US.
Lol!
A teenage Texan I know went to a retreat in Rome where there were participants from all over the world.
Many of them spoke variations of British English and all of the U.S. kids could talk with them, except some of the Texans, because the foreigners ;-) couldn’t understand their Tx accent.
This teenager started speaking with a British accent and then they could understand him! Lol!