Lawn care companies and oyster farms should be hiring workers that are American citizens. If the cheap import labor was dried up, they would be forced to do so. Many of those jobs used to be filled by High School and College kids.
Would help them pay for some of their education and not require such a large loan.
A college kid who worked in lawn care at $150 a day could earn over $15,000 in a ninety day summer. That puts quite a dent in a college tuition particularly at a state college or community college.
They would be forced to hire illegals. They main part of immigration reform is to reform and expand the guest worker programs so there is no demand for illegals.
As for how much money an individual can make operating a leaf blower, that is limited. In my college days(60s) I worked as a groundskeeper one summer, but I also worked for a asphalt paving contractor, both being minimum wage jobs.
Back in the 1980s, I knew two brothers who began as teenagers mowing lawns and grew that into one of the largest lawn care companies in Dallas. They hired lots of illegals.
One of the problems with seasonal visas is that the season starts earlier and lasts longer in the southern tier of states so they are more likely to find H2B workers before the quota is reached, while those employers to the north have a much harder time.
Oyster processors in Louisiana can get H1B workers but those processors around the Chesapeake Bay cannot. A hotel in FL is more likely to get an H1B worker while the hotel in Maine will not.