That's them. With this book they're trying to edge into the popular market, but not too adept at it.
If they want to get this (or any) book into the trade market, there are 2 things they need to do.
1) The paperback should be priced at no more than $20, and preferably between $15 and $18.
2) They need to make it available to bookstores. As an academic publisher, general bookstores aren't going to be ordering from them directly. At the very least, the book needs to be available to stores through Ingram (and maybe other wholesalers like Baker & Taylor) at standard discounts. I looked it up and Ingram shows that it is possible for a store to order the hardcover but it is backorder only (meaning that it isn't in Ingram's warehouses - the bookstore orders it and then Ingram orders one from the publisher, so it may be weeks before it actually gets to the store). It also has a short discount of only 10% and is nonreturnable. These terms are typical for academic publishers through Ingram, but they basically mean that, at best, some stores may be willing to order it if a customer special orders it and pre-pays.
According to Ingram, the paperback is listed as "Not Yet Available" despite a pub. date of 3/7/17. It also has only a 10% discount.
If they've given you the impression that they're trying to reach a wider market, I'd be curious to hear how. As an academic/niche press, they are legit and established, but nothing I see indicates any practical effort to get into the trade market. A lot of university presses have trade imprints now, publishing books that are priced for the general market and available at standard discounts to stores through wholesalers and even distributors. If Routledge wants to do this, they need to change their prices, offer better terms, and try to get industry reviews so bookstores can at least consider carrying the books.