Because laying on a mattress in a shop for 60 seconds tells you nothing about how it is to actually sleep on for 8 hours and JR offer a 30 day no questions asked refund guarantee.
They do but this is our experience with JR
we ordered a mattress and on their recommendation boarded our sprung slatted base.
When the mattress arrived we gave it about a week and after many mornings us both waking up with backache decided to send it back and get another one.
They were very clear that the 30 day money back option could only be used once, if we ordered a 2nd mattress then we would not be able to exchange/return it.
I ummed and arred over what to do and based on the rave reviews on here about how good they were, we went for a 2nd mattress from JR which apparently should have been softer. The 2nd mattress was over £800 and is still giving my partner problems, we have tried removing the board from her side of the bed and it hasn't really helped.
JR also refused to collect the original mattress because they wanted to save money by collecting/delivering at the same time, despite me complaining that we had literally nowhere to put the mattress that was being taken away in the mean time.
So we are now stuck with the latest mattress. FWIW, sleeping on our sofa does not cause either of us to have a sore back in the morning.
We have had the latest mattress about 2 weeks now so hopefully once we have "bedded" it in a bit more things will improve.