Why Immigration Reductions Are Bad

This week I have had a side-by-side study in immigration. We have had two major projects being done on our house at the same time. One is the repairing of rotted wood and repainting of all the trim and wood surfaces on the outside of our house. The second is the replacing of the roof on the old section of our house.  
My painters are a nice family from Mexico who have lived and worked here for very long time. The roofers are an old Durham company who actually put the roof on our addition 21 years ago. All the men sent by the roofing company were American.  
The painters found a number of areas of rotted wood that required a carpenter to fix. Since our carpenter, Joe, has retired I asked them if they had someone they worked with who could do the work quickly. They called a fellow Mexican carpenter who came with his son and did excellent work.  
Here is my experience with these various crews this week. The painters showed up when they said they would, worked diligently, took no breaks except for lunch, which they microwaved in my yard and ate so they did not lose much time going someone else for lunch, they cleaned up everyday, did perfect work and charged me very fairly. They even cleaned up messes that were not of their making. The painters worked from eight until six everyday.
The roofers came late, which was a blessing since they said they would start at six in the morning, they made giant messes and left them, they trampled my gardens, they left nails in the grass, driveway and walkway, they took many breaks for half hour stretches, and they left before lunch and never returned on any day. I know that roofing can be hot and hard work, but as far as I saw no one was on my roof more than four hours a day. They promised to be done today and were not because they did not have enough shingles to do the sunroom roof, but they left at ten in the morning and were not sure when they will return.
I know we have a president who wants to make America great again, but as far as I can tell it is up to each American to make themselves great and the country will follow. The Mexican painters and carpenters I had working at my house were so far superior to the American roofers. I am comparing apples to oranges because the painters and the carpenters were the owners of their own businesses and the roofers were employees, but I never once saw anyone from the roofing company who could be considered an owner or management. I also never had any proactive communications from the roofing people.
I want to support American business, and local business, but if given the choice as far as work at my house I probably would chose Mexican workers if I could get them. Now this is not a blanket statement. I love my American plumbers and American electricians, but they are old and from the good work ethic school.  
I am worried about the pipeline of good workers that Donald Trump is trying to prevent from coming to this country being cut off. Our history has been one where people who are trying to have a better life through hard work come to America to make their fortune. We need those people. Some of the people who have been here for generations are not that interested in working hard.