Based on the data on this page[1] on households with kids:

57% have both parents working full time

28% have one parent working full time and the other not working at all.

The remaining 16% is one full time, one part time.

As another commenter pointed out - while not the majority, it's definitely not an outlier.

[1] https://www.bls.gov/opub/mlr/2020/article/comparing-characte...

In the US at least, it's like 2:1 ratio, maybe 30-35% of families with kids have a stay at home parent.

So, less common, but not an incredible outlier.

What's somewhat interesting is that at both very low and very high income levels, the % of stay-at-home parent is higher. So for people near poverty, or people making top 1%-ish income, it's less than a 2:1 ratio, more like 35-40%. For middle income like $40k-$100k, it's more like 3:1 or 4:1.

At no income level is it lower than 20% stay at home parent though, so not too much of an outlier in any case.