I think it's safe to say that Amazon is like most companies: The more they want you, the more they'll pay to get you. I've heard of exceptional relocation packages (all the way up to "having trouble selling your house? no problem, we'll buy it from you for its assessed market value") being provided by many different organizations to a select few recruits.
Obviously Amazon is enthusiastic about your friend!
I think it's because relocation is a discretionary case by case expense. The standard stuff, like health insurance, is on the "frugal" side, or so I've heard. But that's because you set that up all at once for the whole company. You can't offer a better health insurance plan to an A player the way you can offer a more generous relocation package. Which I will add is little consolation to anyone who already lives in Seattle.
Yes, relocation is definitely an easier place for a company to provide special treatment to a prospective hire than "boilerplate benefits" like medical. I've heard of exactly one case where someone managed to get special treatment in the area of health insurance -- a diabetic who found that the corporate health plan wouldn't cover an insulin pump until he had been on it for X years, and was told "ok, we'll throw in a free insulin pump as a signing bonus".
Obviously Amazon is enthusiastic about your friend!