Let's get this one out of the way real quick;
And are people punished more often because one person reported them or because many did?
Nope. Any number of reports (more than zero) does the exact same thing; they trigger a review for that player's behavior in the match. Reviews don't have any kind of strength or intensity, so more reports can't make it check any harder, and 1 report is the same as 9 in a match.
I understand that if you report these people and they are punished, you will be notified of it.
You don't always get this feedback, and it can only happen when they are immediately punished due to the review triggered by your report in that match. If the behavior in their next game pushes them over the edge for a punishment, you won't be notified even though your report did contribute to that happening. Basically, don't get hung up on not getting notified, it's very uncommon.
In which case a robot bans them instead of someone actually taking a look at what happened. So I ask again, how seriously are reports actually taken?
The automated Instant Feedback System reviews the severity and frequency of their behavior and issues a punishment (or not) based on what it finds and what punishment tier they are already on. If they are frequently toxic they'll likely end up punished and get escalated up the tiers one at a time as they continue doing it. If they are extremely toxic (like using hate speech) you can skip multiple tiers straight to a 14 day or permanent account ban.
