It’s not just physical things. All sorts of intellectual work is being outsourced such as engineering and design work of every kind. Very hard to put a tariff on an email with an attachment.
I am assuming this out sourced engineering service is for a product that is resold in the USA, right? So the incoming product needs to be tariff'ed. That is how you get them.
I did six months of one-on-one Spanish lessons several years ago using Skype with microphone and webcam. Cost about $50/week for three one hour sessions. My teachers, very professional university grads, were in Guatemala and I was in New Hampshire. They delivered a first class product. I would recommend them in an instant.
What would that have cost me here in the States I wonder?
No, one taxes the Invoice and believe me the hours are tracked and there will be an Invoice.