Avg player doesn't buy a few thousand cards at a time. If you buy a high value card from a random seller you should always check it unless you trust them from references.
People only pull out slower tools for valuable, forgery worthy cards.
If someone is buying 1000 $1000 dollar cards, it’s still worth it lol.
Even cheap forgeries cost money to produce, so I wouldn’t expect a lot of low value cards to be forged. If you sort out the valuable cards and do random sampling, you can probably catch the most problematic cases.