A red background can also mean "incomplete", "in danger", "disabled but still there", "not connected/available" etc.
Strike-through is usually associated with "this was here but it's gone now", mostly for lists (like a grocery list).
It also keeps it readable without having to read text on a different background color. I personally find black text on red to be annoying to read, and changing the font color to make it more readable can just lead to further confusion.
If you're showing a list with values that are removed, I would use strike-through personally.