You can get banned from coming to the US if they catch you lying about the reason you're crossing the border. It's a long arduous process and lawyer fees to get the ban overturned. Happened to a Canadian I knew a decade ago when they tried to enter on a tourist visa for business purposes.

I'm sure it's similar in other countries but US has always been very strict given the huge amount of people trying to work there and the very finite supply of work visas.

From my experience you'll also get extra scruntiny if you're traveling solo like this girl. I was secondary screened twice coming for business where they double checked my paperwork and TSA lady in the back asked a bunch of silly questions (like "what is PayPal").