Sorry, missed the Roofer example.
So I take it you are OK with people coming here illegally, Taking Americans jobs, because they work cheaper.
I am afraid you misunderstood it. I made two points: any enforcement of the prices (including those of labor) are (i) unfair to those whom they supposedly are intended to protect, and (ii) impractical. I would add the third, which is the real reason I am replying at some length: by advocating "protections" you empower the government (socialism of fascism, depending on details), which is completely incapable of doing what you want to achieve. You are working against the conservative principles to which you supposedly aspire.
Your remark about illegals is both irrelevant and incorrect. I was giving an example of people being free to buy goods or services wherever those happen to be. This does not involve breaking the law. Outsourcing is in line but not illegal immigration.
As a conservative you should understand that only the employee is responsible for making his job worthwhile, not the government or anybody else. One should be either increase his productivity or agree to lower wages. Only the market knows what our labor is worth.