I'm going to try to be very careful here...but I have a pretty intimate knowledge of this subject. It's an incredibly important, utterly thankless component of the golf business...and I could tell some stories that would really piss some people off.
As golf professionals, most of us get our foot in the door by working the bag drop...and I'm no different. I was fortunate to work at several Top-50 clubs over my 15 years as a club professional....and I witnessed or was a part of every possible incarnation of the bag drop/valet concept.
The bag drop guys at most clubs literally do EVERYTHING. Cleaning, prepping, and staging golf carts for daily play (and cleaning and storage), setting up, taking down, and picking the range (almost constantly at some clubs), cleaning and storing bag-room clubs, meeting and greeting members/guests. In fact, the bag room guys at many large/busy clubs I'm familiar with know the day's tee sheet much better than the Head Professional or Director of Golf, who are usually otherwise engaged inside the clubhouse or outside teaching.
I spent my entire career as a club professional at high-end, private facilities. With the exception of Yeamans Hall, the golf operations side of literally every club I worked at would be utter chaos without a good outside staff. Trust me when I tell you that without this staff, many clubs (golf operations-wise) would be a mess.
There are a couple different ways that clubs choose to compensate these guys. Many still hold on to the gratuity model, which means that the club is relying on members and guests to ensure that it's employees make a livable wage. I worked at a fairly well-known club in the Hilton Head area that paid its outside guys $8 an hour, plus tips. This isn't a bad arrangement for 3 months out of the year, when you can reasonably expect to make an extra $75-$100 per shift. However, the rest of the year, it's pretty tough sledding when you are only bringing home what the club pays you. This club insisted on the highest level of cleanliness, service, and accommodation of its members and guests. Most members own their own carts, and after they have finished their round, the outside staff is expected to "detail" their golf carts with Tire-Shine and Armor-All, much as if they were an automobile...many taking anywhere from 15-20 minutes to complete. Most members would toss you $5 for that and cleaning their clubs -although there were a few who would try to stiff you. Ironically, the shifts where the guys made decent money were actually ones where a large number of guests played. NO ONE ever volunteered to work on Ladies Day, or during the Ladies Member-Guest. Where most men typically tip $3-$20 per bag, you can count on the ladies at this particular club to come through with anything from nickels and dimes to single dollar bills.
This is a club where the members pay a huge premium to own a home, pay well into seven digits as an initiation, and pay dues that are probably over 20K per year by now. So no one is going to sympathize with them for spending probably $100 per year tipping the staff.
My point is this, if you join a club like this, or play there as a guest, just understand that the club has set it's operation up in such a way that these guys are dependent on tips to make their money.
It's kind of like going to Fleming's, Ruth's Chris, or St. Elmo's for dinner. You know it's expensive going in, you could probably go back in their kitchen and cook the damn steak yourself and do as good a job...but are you really going to have an inner dialogue about whether or not to stiff the server? If you have a lousy experience, or poor service, feel free to tip less than 20%. I wouldn't blame you for avoiding the place afterwards. If no one greets you, cleans your clubs, and you walk, I don't think anyone would expect a tip.
I don't like the gratuity model at clubs any better than anyone else here - and I'm embarrassed when I go to a fancy club and someone makes a fuss over me. I typically avoid the bag drop altogether and walk my own clubs over. I always tip the bag drop guys, though, because I know they have to clean up whatever mess I left in the cart after my round, and I know that they are being paid as little as possible.
This is the sanitized version that I doubt anyone will read anyway. You don't have to agree with me, but there is a lot more to it than most folks realize...