I guess shops in your area just don’t have the staff to handle a website that shows stock (if it doesn’t, then having a website for a bookstore at all is… almost pointless), which is unfortunate. But every indie I’ve worked for did have one, and since they had an inventory of stock, transferring the entirety of it online was part of the process.
I work in a used shop these days, though, and we do not have the majority of our used stock online. (Well, I should say, we have about 8,500 books online, but they are not the stuff we typically buy in the main store, which is thousands more. The ones online are older, rarer, and generally out of print. Basic stock sells too quickly, and we deal in SO much volume, there’s no point in archiving, nor do we have the time. You’d need an entire extra staff member doing literally nothing else in order to keep up. Most secondhand shops are going to have this problem, because you can’t just barcode-scan old books like you can with new, 90% of the time.)
All of which is to say, I feel your pain, but… if you’re looking for generally out of print titles, this is a problem you’re going to run into basically everywhere, and it’s not the fault of the bookshops. Older books just aren’t designed, when applied to a secondhand selling model, to be easily transferred to an online shopping experience. Unless all the staff does all day, every day, is archiving for online. And most places are not going to do that; the bulk of the business that keeps us alive is with our customers who walk in and buy in person, always.