I understand what you are saying. We are on different wave lengths. I grew up in Chevy vehicles exactly like these. My dad's first car was 1960 Chevy Bel Air when I was born in 1963. His second car was a 1966 Impala & so on.
Chevy had the Bel Air & later added higher trim levels like the Impala & Caprice.
Mitsubishi switched the trim levels around in one year. I don't think Chevy ever flipped the above trim levels. Trim levels did disappeared and reappeared. My dad even had a Lumina when that sort of replace the Impala line up. After that he went Buick for a few years & then came back to the Impala. After his last Impala, he's owned SUVs instead. Living on a farm, my parents have always had a full size Chevy pickup in their garage, too.
I don't think Chevy ever flipped the Bel Air & Impala trim level names, which is what Mitsubishi sort of did in 2017. Even though the early Bel Air may have been consider well equipped in its day, none of the other trim levels (Impala/Caprice) were ever considered below it. Thus, I always think of the Bel Air as the bottom trim level even in the years it was the only trim level.
By comparison - I cannot view the ES the same way. The ES is not the base level for all years. To me that is confusing.
I still use an Impala (2015) to this day. I will have at least 8 hours of btw driving lessons in one this upcoming week.