We have had this argument before. To employ a professional tredesman today (painter) costs around $60 an hour. Now to do the work the way you suggest is very time consuming and not many people can afford to employ someone at those prices for hours and hours of labour totaling hundreds of dollars to do the job professionally.
Tradesemen have to work according to the requirements and pocket of their customers and the customer usually wants the best job but at the cheapest price so a compromise has to be reached. We all know how the job Should be done but the customer can only afford so much and they usually opt for the quicker, cheaper job. False economy, I know but thats the way it is specially when putting a house on the market to sell, vendors just want a quick freshen up to make it look good for the would be buyers.
The best way to get the job you want is to do the work yourself or be prepared to spend big bucks.