In many European countries (perhaps elsewhere in the world), temple marriages are not recognised as legal marriages (or some sort of rationale along those lines). As a result many LDS couple sin those countries are married civilly first and later sealed in the temple.
Considering how young and scattered the Church is there (not counting all the Scandinavian and British converts that immigrated to the United States), it is probably ideal as well for those couples who have families and friends who are not members of the Church, since they can attend the wedding.
Why is this not done in the United States and Canada?
It is a regular if not common concern among converts or children of part member families who are getting married that their parent(s) will not be able to attend their wedding. It would seem that a civil marriage would avoid that problem.
Is there something inherently better with being married and sealed in the temple compared to being married civilly one day and sealed in the temple the next (or even later the same day)?