@Spysolation
Rubber shoes are recommended to tourists for Croatian beaches because of urchins, rather than them all being razor sharp. Many are just nice and pebbly.
I've spent very many summers on the island of Krk. There are lots of lovely accessible beaches and yeah some inaccessible areas but they're not considered beaches (and neither is the area where she was found). I never used to wear rubber shoes up until a few years ago which was more for stability as it makes going into the sea easier when carrying a baby/toddler. Never stepped on an urchin either - the local authorities usually clean the shallow waters (pick them and throw them back into the deep) early in the season.
Because beaches and sea floor is pebbly and rocky rather than sandy or muddy, the sea water is normally super clear and it's easy to see what you're stepping on. It's not that hard to avoid an urchin.