If I were able to do much in-store shopping this year, I would have loaded up the cart, gone to the counter and wished the clerk a cheery MERRY CHRISTMAS!
In any store that forbid its clerks from answering in kind, I would give the stink eye, note that I was Christmas shopping, that I intended to buy Christmas presents, point out the logical disconnect in buying Christmas presents from a store that doesn't celebrate Christmas, turn on my heel and walk away.
Any store that doesn't get the message after having to restock multiple abandoned carts probably doesn't deserve to be in business...
The only store, in fact, that I remember aggressively trying to avoid the phrase was Sears, which was surprising because in recent years that had used it. I got what I had to get & got out as fast as possible. Sears seemed a little deader than the other places and a little less happy.
Home Depot is another one with a rep for being anti-Christmas. I didn't even go there this year.
I usually say “Merry Christmas” to the clerks when I check out.....the preferred answer as they grin at me is “the same to you”....seems to be the plan of most clerks to get away with it. One clerk smiled and told me how refreshing it was to see someone enjoying the Christmas music...I realized I was singing out, not just in my head. LOL