I'd agree with that, and add to your point about pedaling styles, "familiarity". For me, the shallow loose sand made me think, a) This is much firmer than those sandy tracks I used to struggle through the forest on to get to the in-laws; b) This is just like the Bristol-Bath path all used to be 20 years ago. Whereas I'm sure some people were thinking "Ooo, sand!" I really need to add here that my actual level of skill and confidence on proper loose surfaces is just above absolute zero. And that these are all different situations, IMO, to dirty tarmac.