Comment by WarOnPrivacy

Four incomes is the number of full-time jobs paying typical (most obtainable) wages. Presumably that would be 4 people.

In my market: In mid 1990s one person could afford basic bills on typical, full-time wages. By 2007 living costs had doubled, most due to housing increases. For the next 12 years, wages and living costs mostly kept parity until 2020.

During 2020, basic bills (mostly housing) rose and a typical wage-earning home required ~3 incomes as rents shot up. By late 2021 we were firmly at 4 incomes while everything shot up, especially housing and insurances.