Health and Safety rules nowadays,the riders know the meeting will be re-run ,so don’t really care. Track covers been tried.IMO to labour intensive ,track still has to be prepared to a degree once removed if just bends covered ( riders not happy with dry onto wet).Major factor if raining at start time meeting will not go ahead anyway.No easy way out of the situation.Early call off probably best bet,but with riders competing all over the place finding dates to hold abandoned fixture is a headache.
Thats my thoughts.