Whether it was a childminder or a relative, 10 minutes is too long for such a little 'un to be crying alone.
If you are responsible for a child who is upset for that long, and you are aware of it, you need to do something. Even if you're trying a "time out", for him to cool down after a tantrum, it clearly isn't working if the distress goes on so long.
If you are the responsible one and you aren't aware of it, then why aren't you? If the child is that young, 10 minutes away is far too long. A hell of a lot can happen in 10 minutes. Accidents, for a start, but abductions too. Okay, they are rare events, but they do happen. You can't take your eyes off them for that long.
I've got to be honest and admit that I've always applied the above to my own kids and grandkids, but not to other people's children. I've helped lost kids, and I've kept an eye on others who look like they might be on their own, but I've never intervened and given another parent (or childminder) a telling-off for being neglectful. I've thought it but not said it. Cowardice, I'm afraid, and fear of "making a scene."