Quote:
I don't believe there are many local cover instances anymore.
More directly, there is no local
first class letter rate distinction at carrier offices since March 26, 1944, and at non-carrier offices since January 7, 1968.
The OP's cover contains the wording about the contents being merchandise and openable for inspection, therefore it is a 3rd class mailing regardess.
Looking inthe more antiquated 2020 Scott, they value 806 with several solo rate permutations, and oddly Scott 841 (perf vert) as a "Single franking on local cover", and Scott 850 as a "Single franking on third-class cover". So a bit "apples and oranges" here.
Utilities: certainly, if a local mailing, although many utilities sent with a permit or meter, which couls still exhibit the local rate. Here is the sheet version on a utility mailing:

(Parcelpostguy and I were posting at the same time. LOL)