The San Diego port of entry is the busiest land border crossing in the western hemisphere. The takeaway here should be that the resources to handle immigration along the southern border are insufficient.
If you’re deporting someone, they have to be in custody. They have to deport her to Canada, not Mexico. They likely deal with many other countries and have to arrange for transportation back to all those countries.
I don’t think anyone would have a problem if she was processed promptly and quickly deported or if the confinement accommodations were nicer. That’s purely a resources problem.