I am not a lawyer. But I'd be willing to guess that the difference is that you're a US citizen, attempting to get work wherever you can find it. While you're in that state, you abide by the laws of that state (you pay taxes to that state for income earned there, for example), while also following the laws of your home state (you also file tax there).
And while I imagine accenture's argument will be similar to yours, though much more nuanced, the argument against Accenture will be that those individuals were chosen and use specifically with the intent to bypass local wage laws.
In short, trying to find loopholes in the law, while knowingly violating the purpose of a law, does not result in innocence. Whatever Hollywood says.
I imagine the argument would be along the lines of:
Accenture - Yes, we frequently bus Mexican developers throughout the American southwest. This is because accenture uses many Mexican development shops, and occasionally our clients are interested in having our developers work on site to promote synergy, for small periods of time.
Legal Team - You bussed over a team of 50 devs to Client X, every day, for 2 years. They live in hotels, start on Monday, and end on Friday. This is not a case of the occasional developer meeting with a client as part of a business trip. This is an organized conspiracy to replace the American workforce.
Accenture - While we do run weekly bus services over the border, you will find that in your example, the same individuals do not go every week. Instead, a different 50 were located at Client A on a monthly basis. If there are 200 people working on the project, each 50 will meet for a month. That's four months of busing across the border, while the majority of the time, the team is actually operating from Mexico. We do this to promote synergy across the entire team, not just a select few individuals.
Legal Team - Your honor, we have testimony that when those individuals are in Mexico, their time is split between 20 other projects. When they are in the US, their time is dedicated solely to the client. In short, their claim that they have not somehow intentionally replaced jobs, because they continuously hire and fire different people for the position is patently absurd..
...
But it doesn't matter, because none of those developers are going to bring the suit, at least avanade doesn't hire US developers anymore, and the last few administrations simply haven't been prosecuting US businesses for labor infractions at a historic rate, so I somehow doubt this case would ever occur.