2013 New Strut scam???

I just bought a 2013 Used Volt with about 36,000 miles on it. Been driving it for almost a month with no problems.

About a week ago I started to notice a slight pull to the left. I took it in for an oil change (was at 27% and I want to know for sure when it was changed.)

My trusted mech that I have been going to since 2005 says the right strut is bad. Shows me how when it was on the lift, you could grab onto the tire and lift it about an inch. He says the left one is OK for now but they should be replaced in pairs.

Also the left side driveshaft or something like that is damaged from a pot hole or what not.

Here's my question: Waaaaay back in Auto Shop in 1982, I was taught that the wheel is supposed to be able to be lifted and have that much play. The teacher told us it was a scam to make you get new struts.

Whats's going on here????