When I were a lad (nobbut a few years ago) the green stuff in "Salad" was a few leaves of limp lettuce - designed mainly to make the plate look fuller.
It was (effectively) inedible, but at least inoffensive and cheap.
Now "salad greens" seem to involve a load of stuff that previously I would have designated as "weeds" - dandelion leaves, rocket, escarole, mizuna, beet tops, lambs lettuce and god knows what other horrors.
It all costs a small fortune, tastes vile (unless smothered in expensive balsamic dressing) and is a complete fraud on the gullible consumer by the major supermarkets - aided and abetted by the usual foodie twits.