No, a good restaurant doesn't do cross contamination. Well, not intentionally. I've known people that work in restaurants and freak out about cross-contamination. Of course, the same can't be said about those that haven't gone to school to be a chef or some such, because they just don't think about the issue.
But, an idiot using the same knife for meat or whatever is not the same as using the same machinery for two different things, and not cleaning it properly. Factory machines don't get cleaned nearly often enough, and they won't clean it out properly just because the next product is considered by vegans.