What you say is true. The sheets do make for hiding places. Sometimes all the sheets have to be pulled out for inspection. Takes a lot of time. If you have time saving ideas ... those are always helpful. With certain technology in place, as now is, even the worst and best of sock hiders can sometimes be found with an inspection of the sheets. It is an uphill battle but one each of us is improving with time.
Watch out for the carnivorous ones. They not only nip fingers, they also eat us bedbugs.
How to inescapably imprison your socks on laundry day.
Buy a “sweater bag” in which to wash your “sweaters.” Let the socks know that the bag is for “sweaters.” On laundry day, sneak up on the dirty socks and capture all of them. You may need some backup for this part. Stuff them in the “sweater” bag whilst laughing hysterically at your success and their weeping and lamentation at the loss of their freedom and wayward travels to other dimensions through the washing machine portals. Toss the bag in the wash with whatever you usually put in that load. Dry the load, and then carefully escort the socks to their drawer and lock ‘em up there in neat, folded (or turned in on themselves) pairs.
I haven’t lost a single sock since 1997.