Not entirely true. For the diversity visa (green card lottery), there are (extensive) medical and background checks, but the US consulate does not consider skills and resources beyond verifying that you meet the minimum requirements (high school diploma). The consulate interview for this category is basically a rubber stamp.

However, as others pointed out, the DV is a small fraction of green cards granted, and the process for family based immigration may differ.

Source: I went through this process.