^This is especially true for high-priced lineaged items. I would be very wary of higher-end tenius pieces especially and ask for proof of lineage, there are a lot of mariculture mimics of these out there.
This being said, there is often little to no need for proof of lineage or it can be impossible to track down direct lineage for obvious or more common pieces that have been in the hobby (think Green Slimer, Strawberry shortcake, Red Dragon, Hawkins Echinata, Tri Color Valida, Pink Lemonade and misc). Often times these pieces are either unique enough, common enough, or cheap enough that morphology/coloration alone has been generally accepted for proof of identity.
For example, I am unable to provide proof/trace of lineage of the frags I shipped to you today (i.e Aussie Gold, Pink Cadillac, WWC Yellow Tips, Hawkins Echinata), but they are common enough that their coloration/morphology should be enough verify their identity.
The "Fake Pearlberry" I shipped you in the as a freebie, is an example of unproven lineage. It was originally sold to me as an ORA Pearlberry without proof of lineage. As it has grown out, I don't think it resembles a Pearlberry either. As such, I now call it "Fake Pearlberry" so that it's non-lineage is clear.