Say you manage to get a job offer and put in your application for a residence visa under the skilled migrant category, will immi department call your employer to harass them for information or get them to attend an interview?

I don't understand why employers are so reluctant to hire foreign labour then. From what I understand, under the SMC, there are no labour tests required. No interviews, no hassle for employers at all.

My understanding is that they just have to write a simple letter stating "I am employing xxx as a xxx" and that's that?