My local grocery store has a handwritten sign, "ten item's or fewer" that is put out for different times of day, instead of a dedicated lane. I have shown it to the manager. I have marked out the errant apostrophe. Twice, I have turned it into a smiley face, using the apostrophe as an eye. I go twice a week. I continue to see new handwritten "item's" and I am about to buy MORE than I really need, just to avoid that blasted sign!!!
A great BBQ place around here offered root beer flaots. Yumm!! They did fix the spelling when new menus were ordered, but my family still calls them flaots.
In HS, and again in college, I had English teachers that offered points for real life examples of grammar errors. Sadly, many were found in the college cafeteria.
I DO carry a red pen in my wallet. I HAVE used it.