The Mystery of the Tennis Ball and the Walker

You've seen them shuffling along hospital corridors and waiting in line at the drug store. Bent, elderly people leaning heavily on their walkers. And usually, for some mysterious reason, those walkers are affixed with slit, lime-green tennis balls. 

Which would lead one to assume there's something inherently flawed about the design of the walker as we know it. If they work better or are somehow safer with tennis balls jammed on their ends, why don't their manufacturers just make them with tennis ball-like fixtures at the bottoms?

Apparently it's more complicated than that. Most walkers are made with rubber grips on the back legs, making them less likely to slip on slick surfaces. But their users find them too sticky, so elderly people -- or, I'm guessing from experience, their long-suffering middle-aged children -- add the butchered tennis balls to make them slide more easily on surfaces like linoleum and tile. 

So my next question was: if walkers require this adjustment and the manufacturers of walkers aren't taking the cue to construct them differently, or at least provide features that can be swapped out to address different types of terrain, why isn't some enterprising entrepreneur stepping up to fill this marketing niche? I needn't have worried.

The Internet is alive with mutilated tennis balls just waiting to help grandma get to that quilting bee without breaking a hip. Walmart, for example, carries a product called the Drive Medical Deluxe Walker Rear Tennis Ball Glide, a set of two for just $37. But there are loads of other choices, some even displaying jubilant laughing faces because, after all, what's more fun-filled than being 80 years old and trying to maneuver yourself down a crowded city sidewalk propped up by some metal tubing and a couple of fuzzy guffawing lime-green orbs?

So, here we have a neat little case study of a product on the market that requires adaptation, and a seemingly endless number of manufacturers that have moved in to fill an obvious marketing need. I just have one more question: why do they still have to look like tennis balls?