Somewhere, somehow a caddie needs to be getting close to $100 a loop. Sharing a caddie between two bags is so annoying that I never intend to accede to that arrangement again. But perhaps $70 is a better estimate. If I had to pay even $70 (whether you call it a fee or a tip or a subsidy from the club to hide the true cost) times the number of rounds I play at my club in a typical year that would be at least $5,000. And if the practice were as universal as some people seem to think it would be, presumably I'd pay something like that every time I played away. And to repeat, I will not willingly suffer a dual-loop caddie arrangement in the future.
The 60-70 years olds I play with regularly are a mixture of about 20% cart riders and 80% walkers. And probably 80% of the walkers use a three-wheel cart for the bag, some push carts and some electric ones. The one guy I play with regularly in his 80's started riding in a golf cart a couple years ago after an illness. Before that he walked and used a Sun Mountain cart. I'd say the ladies at our club probably are less likely to use golf carts than the men of the same age but still a mix of riding carts and Sun Mountains, almost none carry their bags on their shoulders.
My handicap index is 17.7 and I am 49 year old, in perfect health. I walk and either tote or push on a three-wheeler my own bag depending on the weather, the terrain and whether I intend to play more than 18 holes in a day. My ideal golf experience would be to walk straight from my car to the first tee without seeing a single paid employee of the club, shake hands with the people I'll be playing with and start walking and hitting the ball immediately, continuing until the round ends. I require exactly zero services, staff, waiters, caddies, helpers, marshals or other paid or unpaid help to enjoy my round. I tolerate the usual miscellany of clubhouse and pro shop staff and what have you but would not consider belonging to a club with ubiquitous caddies. I wish my own club would desist in having "bag boys" and such but doubt that will happen any time soon. I will admit that a good dining room (which we have) adds a lot to the club but would shed no tears over doing without that luxury.