The Chevy Suburban and the Ford Expedition are 4wd systems not AWD. This means you only engage the 4wd system when you cant get by with 2wd. The 4wd is not engaged when it rains or there is a light snow. In fact, many might never need to engage 4wd at all in this area. If they drive up an unplowed driveway or on an unplowed road, if they back their boat down the wet ramp...perhaps, but once thats done it goes back into 2wd. You generally do not drive for extended periods with the 4wd on.
The AWD system found on the new Yukon Denali is always on and the system will spin certain wheels certain speeds depending upon conditions. Thats AWD.
4wd adds 250 lbs of weight to the vehicle and is the only true difference between with and without. That said, 250 lbs is a bit of weight to carry around all the time. It will zap about .5 to 1 mpg. Over 200 to 300k miles thats a lot of gas.
The only reason a livery or Uber driver should get 4wd is if they care about resale value. Many people feel they need it for NYC, but the reality is they dont know what they are talking about. They will very rarely engage it if ever in NYC. Most probably after the first big snow storm they will go out before the roads are plowed to test it out, but that will be the only time they will need it.