The difference is that room reservations have a different refund policy and it is unlikely that you will arrive at WDW to find that you don't have a room and the parks are all closed. Mobile food order is done when you are on-property (or nearby), not days ahead of time before youve even boarded your flight - and when was the last time someone ordered food only to go pick it up and be told, "Sorry, we'reactuall out of hamburgers" AND not get refunded?
Again, G+ only guaranteed the ability to choose from the available times - not a guarantee that you would get a specific ride within a specific window if time, so the products aren't comparable for this scenario.
I'm not familiar with what other US parks allow guests to pre-book specific rides in advance, so I can't compare. The parks I know of either use Universal's system or something closer to G+ or ILL as a day-of purchase.