They are staying this side of the border because they can’t go into Canada unless they are poison vaxed.
The convoys include a lot of vaccinated truckers. the truckers are protesting mandates and heavy-handed COVID polices. This video includes a clip from a US-Canada border station showing a US convoy entering Canada to join the Freedom Convoy.
https://www.youtube.com/watch?v=cBp6KkHsZXs