I don't have any data, but it wouldn't at all surprise me if single/business travelers are way more likely to cancel or change flights, and this is just pricing that into the ticket cost.
Business traveler maybe. Not my money and business stuff happens. (Usually they want you to book non-refundable because it comes out ahead in the end.)
Which is why the people involved take good care to prevent anything from getting in the way of those plans.
If you miss your flight when travelling solo, you disappoint only yourself. With a family the number of disappointed people increases accordingly.
From my anecdata, being single greatly increases your chances of being bumped off a full flight. And it's a lot cheaper and easier to compensate/redirect one person than a family of four.
I did once have an airline offer me something like $1500 USD and 50,000 bonus miles if I was willing to cancel my flight, but that was days in advance.
I'm not sure that's true. The airlines are gambling that at least one person will miss the flight for whatever reason, and they'll get away with overbooking.
But, of course, when they loose that gamble, it's really a passenger that looses. The house always wins.
Not always the case, you could be physically removed from the plane because the flight is full:
https://www.flyertalk.com/articles/overbooked-united-flight-...
When I rebooked, the airline gave me a credit for the round trip flight in total. I only had to book a one way ticket on the last leg, so I obviously was able to "afford" the flight without additional expenditure on my part.