This is a pretty broad generalization. As someone who has been in business for many years, I know the installer is not always paid what you are charged for installation. If there are 2 men on the job, they have to share the money. They also have to buy the tack strip, nails, seam tape, and any other things needed for the job. That comes out of the per yard rate. A good installer should carry insurance, he has to pay for that. He has to pay for a vehicle, and vehicle insurance. So realistically, by the time the expenses come out of the money, the hourly rate can be low. When my husband was subcontracting installation work, if he needed to have a "helper" he had to pay them at least $8.00 per hour. If the helper was a "mechanic", he got 1/2 the job. In order for my husband to stay in the black in our business, he had to gross $1000.00 per week. It sounds like a lot, but he aslo had to pay his own social security (both parts) and income taxes. He was required by the state to have a license to do business, that was over $600.00 per year. You don't install flooring to become rich. The first year we were in business we grossed $185,000. At the end of the year, we netted only 13K out of it.
After 20 years of being on his knees and doing thousands of houses, I can tell you that he was tipped maybe 5 times, and each time he was amazed. He was never tipped more than 20 dollars, so if the OP feels like tipping, believe me the installer will appreciate it.