Wood is safe, but since it's organic has the potential to fuel the growth of molds, bacteria, and other microorganisms. I'm not sure the best way to sanitize wood from these elements? You could light the wood on fire, but then you wouldn't have any wood leftover.
I've heard the opposite, that wood has anti-microbial properties that results in less cross contamination than plastic, even though it is harder to sterilize. For example, here is one study on cutting boards[1].
You can seal woods (polyurethane, linseed oil, etc) and they take well to disinfectants (UV, povidone iodine, etc) and can be submerged in common commercial disinfectant washes.
It's just uncommon in a commercial kitchen because it costs 4-5x the price, depending on how many you want and how many you'll destroy from use over time. A cheap steel implement in a commercial kitchen will last 4-5x the lifetime of a wood one but that same wood implement will last just fine in a home kitchen.
If you are using wood to avoid plastic but coat your wood in polyurethane or any other fossil fuel based compound, I kind of feel like you’ve gone full circle back to consuming plastic.
Wooden spoons go in the dishwasher and then they're perfectly safe. Wooden chopping boards have been shown to be safer than plastuc, because they don't get the cuts that plastic boards do, which harbour microorganisms. Cuts in wooden boards close themselves up.
I don't know where this "unless the surface is sterile it is significantly dangerous" thing comes from. How many people have died from bacteria that grew on wooden utensils that were regularly washed? Is it anything other than zero?
