If I think about charities not being "needed", in the context of the charity I volunteer for, I'd say that it's too simplistic to expect Government (ie. the taxpayer with the government as the administrator of tax) to solely be responsible for all the problems of the country.
I agree government should be tackling the root causes of societal scourges such as poverty, homelessness, crime (all of which are strongly linked), so that more people are pulled out of poverty and don't need to go to food banks. Eliminating all these problems is never going to happen, so charities have to work with government.
what I see is a blame-game, people blaming government for not "fixing" everything instead of seeking to understand the role of charities in society. For example, we do a lot of signposting towards government aid and available funding based on eligibility, because our clients are often inaware of what they're entitled to, don't want to go on benefits (too proud, things they're not worthy, think others have greater problems that themselves), and need support to set them on the right track. We encourage them to use the ringfenced funding available in the NHS for counselling, we give them the dignity to help themselves and in a lot of cases, all they need is to be pointed in the right direction and given encouragement, to get their life back on track.
good charities like the one I volunteer for, need to be recognised for the benefits they bring, rather than being seen as a negative.