This is going to come off smarmy - but that's not my intention.
Vets in general know very little about pet nutrition - Science Diet is pimped by Vets across the Country and most actual animal nutritionists deride it as swill - full of fillers and crap.
Exanthematicus should not be fed ground beef, ground turkey or rodents. A SepticZone care sheet and LLL Reptile blurb should not be quoted as reliable sources for animal care of any kind.
Savs are specialized insect and mollusk feeders - and they have adapted dentition, metabolism and digestion as such. There's no need to feed young savs anything but an insectivorious diet.
You're right - very few sav owners feed their animals the correct diet - but that's out of common misconceptions and ignorance than due to a lack of suitable invertebrate prey on the market.