It’s marketing.  Give Nike credit, they were touting the barefoot shoe experience years ago (I owned one of the first pair of Frees). And if you walk into a big running shoe store and ask for minimal they are going to show you the Nike Free first and may not have any of the other options at all.

I wouldn’t call the Free a minimal shoe either, but it is a lot “less” shoe than many running shoes on the market. I bought a pair for comfortable casual wear a year and a half ago, and I did go for a few runs in them to see what they were like. Turns out, I loved how light and flexible they were compared to my Brooks Glycerins. Now I run in two pair of Brooks racing flats and Vibram Five Fingers. The Nike Free, which feel like slippers, served as my “gateway” shoe into a better world. Just like Pete has written on this blog. The Free has a time and a place and I’m really glad I bought them.

I’d concur with your observation re trail vs. road races. Part of it may simply be that trail runners are more likely to have the “simply” type of attitude toward things. There are also a number of prominent trail runners like Tony Krupicka who help design and promote more minimal shoes, so that certainly helps. Also, outdoor stores like REI and EMS tend to stock a lot more minimalist models than would a typical sporting goods store.

Perhaps most of all though in terms of sales, I think trail runners are less likely to be beginners or fitness joggers, and thus they are probably a lot more likely to be discerning in their shoe tastes. They probably know what they like, and are more aware of what others are wearing. A lot of folks who go into a shoe store, even a running specialty store, are not buying shoes to use for running. Thus, these sales data include sales of a lot of shoe that will never actually be used for their intended purpose. People looking for a pair of “sneakers” are more likely to go with what looks familiar to them.

I think as well there are two other reasons: 

People believe they need more cushioning for roads as they are harder but with trails being a bit softer they are willing to go with less.

Also, particularly from a technical point of view it helps to have more ground feel on the trail so perhaps more conducive to these shoes.

Do you know where I might find information on the size of the specialty run industry in terms of number of specialty run retailers?

Many thanks in advance

Possibly customers who overpronate very slightly and/or who seem to have more of a midfoot strike are given more options to choose from now that retailers are armed with more knowledge, rather than just shoved into a mild support shoe…. at least in decent specialist shops.
Or maybe just due to an increase in orthotic sales, ha ha.

Or simply that the whole fitting process based on pronation control isn’t all that meaningful.

I just went on competitor.com and complained about a ridiculous “5 shoe buying tips” post. I don’t understand how an untrained or barely trained employee at a running store can tell by watching me walk has any basis on telling me what kind of shoe I need. I’d only take advice from an expert who gives sound advice, like yourself.

In my circles, I’m known as a runner and people often ask me for advice on picking out running shoes. I tell them all the same thing – try on as many brands as you can and as many styles as you can. Run in them, and pick the one that feels best. This might not always work because buying running shoes is a trial and error process. None of this “arch height” BS!