I think this is often a dumb complaint and it shows itself in other contexts sometimes. There's a natural floor to income, it's $0. But there is no ceiling. So naturally if you want to give a sampling of scenarios covering most people, most examples will be high earners (even if there are fewer of those) because how many meaningfully different scenarios are there between $0 and $50k of income?

EDIT: Another corollary of this explains part of why income inequality increases over time. As markets become more global, the upside for successful enterprises goes up - there are a lot more potential customers. So today someone at the top of their field can have a much higher income than he could in the past, whereas the income floor at $0 is unchanging.