Everyone is responding like he did get scammed, but I'm not so sure. Was the work done illegally? Almost surely, I'm not arguing that. But to be scammed, he must have not gotten his money's worth.
Did they do a good job and use a good product on the driveway? Did the driveway have alot of cracks and other imperfections before they started? Are they well filled now? $50 extra is not really that much if there WAS in fact alot of existing damage. Just because they didn't price it right at first and had to ask for more doesn't mean your neighbor was scammed, it just means they didn't price the job correctly.