Agreed^
I worked at a dealer for over 16 years. I once tried the do it yourself alignment in my garage with a portable FE aligner that an old friend had. Did an alignment on my Dads car,(was a 01 Buick Park Ave.) took it to work & put it on our Hunter FEA machine, the toe was dead on, camber was within 0.3 but caster was off quite a bit on the left side. I set it @ +0.8 & the Dealer machine showed +1.9. I think that was because he didnt have the swivel plates that are needed to do it right. If you know what you are doing, it can be done with good results.