California's locked case law for handguns, BTW, is satisfied with a little lock holding the zipper on a soft case. It doesn't mean "theft proof". A soft case without a zipper could be hard to secure, I guess.
WRT carrying a long gun: some cities have ridiculous laws about "brandishing" that interpret "brandishing" as "any situation where the gun is visible." That's why people walk around with soft cases. State law, however, does not require long guns to be covered when carried.
Ranges, public and private, can, of course, make their own rules for safety and any other reasons.