The AMC does NOT take a split of the appraisal fee. If anything, it's the appraiser taking a split of the appraisal fee. The lender pays the AMC $zzz to fulfill an appraisal request. The AMC (unfortunately) has the option to fulfill that in whatever manner they choose - so long as it meets the lender's expectations. Sometimes they send someone on staff (in which case, the staff appraiser is paid a salary + comp, and NOT part of the appraisal fee), and sometimes they sub the fulfillment out to a 3rd party provider (the indie appraiser).
Regardless of the method of fulfillment, though, the fee paid by the lender to the AMC IS the appraisal fee. The AMC isn't keeping 'part of the appraiser's fee'. IOW - the AMC isn't taking a 'split' of the fee.
Obviously I succumbed to temptation...