You're absolutely right. Rasps is a local term for raspberries. It's mostly used by older folk - perhaps I'm showing my age! :)
Back in the day, prior to about the late 1970s, raspberries were picked by hand mainly by the "gaen aboot" ("going about") folk, or travelling people, who worked seasonal jobs throughout Scotland. There's an excellent book about it - "Yellow on the Broom," by Betsy Whyte. In later years, student summer labor took some of the work, and when Britain became part of the EU, many Eastern Europeans came over to shoulder the work.
You're also right about the quality of Scottish raspberries. But I've never found them to be overly expensive. Perhaps because the ones I've purchased in the Scottish supermarkets haven't had far to travel from where they were picked.
Anyway, for anyone travelling to Scotland (or England) this summer, be sure to try some rasps (raspberries)!