They didn’t catch the last bus so they were late for school:
=> Owing to their failure to catch the last bus, they were late for school.
Nam doesn’t go to school on time as he misses the last bus:
=> Due to missing the last bus, Nam doesn't go to school on time.
The farmers grew a lot of flowers since they could get profits:
=> Because of the profits they could get, the farmers grew a lot of flowers.