If you read those studies the cases usually involve people with prior health complications, who were fasting, or took the juice in an unusual context.
Turmeric and Cinnamon both contain more oxylate than ripe sweet starfruit, and spinach, beets and chard are very close.
Vegetarians/vegans ingest far more oxylates than meat eaters just because most veg contains it.
Even if oxylate is present in a substance, some of the oxylate can be soluble and some insoluble, for instance the oxylate in turmeric is almost all soluble and available for uptake, levels in cinnamon are only 6% soluble.
Calcium in the diet tends to bind to oxylates making them less soluble, so using high oxylate foods in a low calcium diet means that more soluble oxylate will be present.
In the gut, Oxalobacter formigenes, a common part of the internal microbiome breaks down oxylate, but the presence of that bacteria varies in individuals and may be totally absent after antibiotic use or during certain disease states.
I read a few publications on oxylate in general and found this one directed at vegans to have some good information.
https://veganhealth.org/oxalate/#vegetarian