You can't generalise because the cost of essentials like housing and childcare vary so much.
The difference in money left over after paying rent/mortgage and childcare could vary by £2/3k per month in extreme circumstances between households with the same income.
Plus if you look at the breakdown in the assumptions, they're all over the place.
Apparently a childfree, non pensioner couple only needs £27k before tax to be not in poverty, so I'm not sure why they think two adults can live on this amount, but add in 2 DC and suddenly you need £70k? Or if you tell it you have a baby and a toddler, it claims you need over £90k

Was the survey designed by one of the £100k income 'isn't that much' London Mumsnetters?
We're two childfree working adults with relatively low outgoings and we pay out a lot more than a lot of the assumptions in the breakdown.
Eg less than £6 a week each in pension contributions, that's only just over 1%, most schemes require far more than that.
£6 a week for water for the household, ours is nearly twice that.
£16 a week for gas and electricity, ours hasn't been that low for years.
Rent about £450 pm, there's not many places that you can rent even a 1 bed flat for that little.
etc etc