You misunderstand.
Yes, the single actual cron job gets executed every minute.
But, you define the actual schedule using laravels scheduler. If you read the entire docs I linked to, you'll see that you can schedule something to run daily(). So when the cron job runs (every minute), it checks laravel to see if there's actually something to do. If not, it doesn't do anything. Then it checks again another minute later to see if there's something to do, etc...
What this let's you do is instead of having to have 30 cronjobs set in crontab, you can just have 1, and all of the scheduling is done in code instead of having to have a separate cron job for each one. Read the docs...