Very interesting posts, thanks.
The market in the USA sounds very similar to that of the UK: Head Pro much better off than the Asssistant Pro, both in earnings and working hours. A Head Pro in the UK, like USA very dependent on region and club, will take home in my experience anywhere between $60k to 150k. Most will be at the bottom end of this scale, around $80k. Earnings come from a combination of retainer/salary/teaching/retail. All self-employed, no company car etc. He will have to employ Assistants and Trainees himself and pay them out of his own pocket. Trainees don't earn enough to survive, so most have some kind of family support until they qualify and become Assistant Pros, who normally also earn peanuts. Competition for the decent jobs is absurdly high - with hundreds of applications for any jobs as Head Pros. Again like USA, the "old boy network" together with "friends and family" connections is often the deciding factor in who gets the job. In recent years (the last 10-15) even these good jobs are less lucrative with clubs and owners stepping in and changing the contracts when someone was "earning too much". They could do this because the PGA GB&I kept (and still do) churning out 200-300 new pros every year until the market was saturated beyond belief. So it was a case of "take it or leave it" when the new contracts were offered.
Many PGA Pros left the industry for jobs such as semi-skilled tradesman or tried to retrain in other industries where they could earn more and work less. Many, especially younger guys and gals, went abroad to the new golf markets in Continental Europe where conditions were better.
The PGA GB&I had a forum facility on their website allowing PGA Pros to interact and there was a thread called "Too many Pros, not enough jobs" a couple of years ago which caused a heated debate which was so embarassing for the PGA that they pulled the whole forum under the pretence that there were "legal" issues which they couldn't control!! It has never been brought back.
Slowly however the same kind of development as in the UK has happended in many of the other European countries, but nowhere near to the same extent. Golf pros are generally better of on the Continent than in the UK. In Spain and Portugal where the UK influence is pretty high in terms of resort management, the conditions for pros are similar to the UK - but at least the weather is better

In northern Europe (Holland, Germany, France, Switzerland, Scandindavia etc) things are better, with many Pros being able to operate as full-time teachers due to the higher demand offered by growth in the numbers of people taking up the game and a better ratio of Pros per Golfer. Increasingly though they are having to pay more to work at the facilties and finance every aspect of their teaching themsleves, thus increasing profit for the facility at the cost of the pros. This development shows no signs of letting up.
I know a couple of guys in the US, who are working at big elite resorts as Head Pros/DoG making pretty big money, but that seems to be the tip of the iceberg. Again, thanks for sharing your knowledge.