You’re evidently highly ignorant of reality if you think that actively supplanting those of the home culture with those of a foreign culture will have no impact. Anyone with a basic grasp on history and group psychology understands this conflict.

And yeah, I’m sure the bricklayers go through the Bricklayers Australia Commission to get properly certified for bricklaying.

So what?

“And how do we even qualify those migrants from nations with poor infrastructure? ”

Educate yourself. Please. Anyone migrating under the “skilled” stream MUST get their “skills” assessed by a relevant Australian assessing authority. For example, if you are an overseas educated engineer and planning to move to Aus under the “skilled” stream, your education and work experience must be assessed by Engineers Australia first, and no, it is not a giveaway.

“Are we to be called racist or bigoted if we were to challenge the genuity of a migrant’s claim to experience, despite having an uncontactable employer who he claims has no phone line?”

That is exactly why you have relevant assessing authorities, no need to press the panic button.