The better shops around me also have trails/MUPs right outside their door. I would encourage people to try the bikes they are considering, since I think more often than not it will help deepen the interest.
I dont try a bike before I buy, but I also only buy frames and know the geometry I want for the style of bike I am building up. My wife rode probably 6 road bikes from 3 different stores before she found what she likes. The geometry of each was slightly different- and slight differences are noticeable.
Test rides can be beneficial and should be encouraged.