Why institutions should be registered?

Why social activists, voluntary organizations, non-profit organizations (NPO) and Non-governmental organizations (NGO) are registered?

What are the advantages and flaws to register such institutions?
If their activities are voluntarily and charity for the welfare and social development.
To solve the above and in order to consolidate the activities of NGOs

– Transparency and accountability.
– Donor recruitment assistance.
– The effective use of technical assistance, financial.
– Coordination between NGOs and government departments
– Regulate and monitor the work of their activities in Afghanistan.

Ruling and legal character needs to register.