Those cones could be construed as being a hazard 
I've tripped over a warning sign in a supermarket before; honest!
With life comes an element of risk, but I'd guess with some certainty that we've a greater risk of crashing into someone and killing them on the way to work, than a trailing hose we put out tripping someone and killing them.
Of course there's a risk. There's two blind fellas I know in Chepstow who walk with just a cane (though I think one has a guide dog now, and I clean the windows of the other). And I once reversed in a tight spot and trapped the stick of one of these blind blokes under my rear wheel, which caused a bit of a kerfuffle.
Ian_Giles has also had problems with trailing hoses and getting 'told off' from the wife of this same blind bloke; he put a post about it here. She's very protective of her blind husband.
But I think we can only take reasonable precautions and make sure we're insured and keep our fingers crossed that nothing happens.
It's only a hose at the end of the day and there's far greater hazzards out there caused by other tradesmen.