I don't really see an explanation for the crucial fact that walks merge, which together with the fact that walks can't diverge means that the 1/10 chance of picking the same card at the start invariably increases towards the end.
>. Their walker is equally likely to be on any type of card from the deck (it was shuffled), so there is at least a 1/13 chance of stepping to the spot your walk visited. Since you both use the same rule for taking steps then they will subsequently continue along the same route as your walker and so end at the same card