I was reading a review for an old Japanese textbook, and the reviewer says the following:
“This made it necessary to teach totally unnatural expressions in the earlier units of the course, such as the infamous yasai ga arimasu ka?, yasai o kudasai, of Unit 1 (1.23).” [Context: he was talking about a textbook in which keigo constructions weren’t introduced until late in the course].
I assume that means “Do you have vegetables? Please give me some”. Is that really all that unnatural?
野菜がありますか？野菜をください。
No expert here.
The first part might be a bit direct. A bit like トイレはどこですか？ vs トイレに行きたいんですが
Thinking in English, that’s a bit like saying. “Do you have vegetables? Please give me vegetables.” which is strange too.
I feel like this is probably not the best place to ask – not enough high level/native speakers. https://japanese.stackexchange.com/ might be a better bet. “Unit 1 of a beginner’s textbook” language is always going to be at least somewhat unnatural, of course.
(I suspect that the level of keigo that would have been considered normal/natural in a customer-to-shopkeeper interaction may well have fallen since the 1950s, but I have no evidence for that.)
Also no expert, but - yeah, feels way too direct. I feel you’d do something more like 野菜を買いたいんですが, and omit the direct ask entirely.
Also who shows up at a store asking if they have any vegetables? 
It’s also interesting that the reviewer apparently doesn’t think ‘kudasai’ counts as keigo.
That’s the only part I find unnatural really lol