Bluebelle - you state that most charities take such big cuts that half the money doesn't reach its targets. Here is a summary of the annual report of Save the Children for 2017, the latest available. Since their year end is 31 December the 2018 figures are not yet published. The accounts have been independently audited.
£000
Total funds 406.558
fundraising exps 38,050
charitable acitivities 370,525
Other expenses 512
Total spend 408.063
Deficit - 1,505
Investment income/gains + 2,155
Net surplus 650
I think that you can agree that spending of £38,562,000 is somewhat less than half of the total income of £408,713,000 and that 90.6% of the total income (including investment income)
I was a volunteer for SCF for 20 years whilst I lived in the UK and their aim was always to use around 90% for charitable activities and they have stuck stuck to that aim. I think you will find that the other major charities have similar aims. I am aware that SCF along with Oxfam and others have ongoing problems with sexual harassment amongst the overseas workforce but that should not cloud their financial results and their main aims.
Should you wish to delve deeper you will find the Annual Report on their website.