The kicker is the next code;
P2801.6.1 Pan size and drain. The pan shall be not less
than 1 1/2 inches (38 mm) deep and shall be of sufficient
size and shape to receive dripping or condensate from the
tank or water heater. The pan shall be drained by an indirect
waste pipe of not less than 3/4 inch (19 mm) diameter.
Piping for safety pan drains shall be of those materials
indicated in Table P2906.5. Where a pan drain was not
previously installed, a pan drain shall not be required for a
replacement water heater installation.
The last line makes the whole thing ridiculous. My gas water heater installed last year has a plastic pan underneath with a capped drain. First year my water heater ever had a pan and there is no floor drain in my laundry room (sump is at the other end of the house). Do I need a pan / NO do I get a pan? YES Will it help anything? NO!