If you take the time to review a resume thoroughly and ask thoughtful technical questions about a candidate's past work in the phone screen, the phone screen is almost always going to be a painful and embarrassing experience for a lying candidate. And such a candidate will virtually never make it past a reference check.
The problem is that most companies are lazy. Hiring managers don't read resumes closely and wing it (i.e. jump on phone screens without preparing). Reference checks? What are those?