FormerlyHemlock
Hero
In a medieval-ish society, especially one with illusions and enchantments, assuming an item of any real worth (and we don't care about the cantrip in any other situation) then the coins will also be examined.
Which brings up an interesting point. For anything of real value, D&D people have a very real incentive to ensure there's a test for minor illusions and enchantments. And boy is Friends easy to defeat if you know the ability exists at all. Much like biting a gold coin to make sure it's real.
This is one of those setting-dependent issues: high magic/low magic. I happen to enjoy games where PCs are unusual, magic is rare, and the gameworld equilibrium revolves mostly around the mundane. The main reason for this is that it makes it easier to justify giving adventures to the PCs (in a high-magic setting, bounded accuracy + semi-common NPC spellcasters = all the dungeons have been cleared and looted already) but as a side-effect, it makes NPCs less savvy about magic tricks the PCs/magic monsters could play, and that is good too IMO[1].
Real-life people have a real incentive to check for counterfeit bills, and yet they often don't, because counterfeiters are just so rare.
[1] What's more fun: players having to diagnose dastardly plots like a Rakshasa hiding in the palace, or a king who is so illusion-savvy that he automatically tests everyone for Disguise Self and therefore can't be fooled by a Rakshasa in the first place?