Thanks for this very important question.
Breastfeeding save lives, reduce the risks of mortality and morbidity, contributes to the economic development of a country, its environmentally friendly and evidence has proven that its all what a baby needs during the first six months of life...when complementary feeding starts
please see:
1. Breastfeeding in the 21st century: epidemiology, mechanisms, and lifelong effect (https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(15)01024-7.pdf)
2. Why invest, and what it will take to improve breastfeeding practices? (https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(15)01044-2.pdf)
Breastfeeding, and exclusive breastfeeding during the first six months of life is what should be considered the very first food system....there is an important article see below that illustrate this concept
https://onlinelibrary.wiley.com/doi/full/10.1111/mcn.13097#:~:text=Breastfeeding%20has%20been%20described%20as,Jelliffe%20%26%20Jelliffe%2C%201978).
That highlights the reasons why breastfeeding is the first food system, is sustainable, equitable, environmentally friendly but requires system-wide protection and support and the society as a whole as a responsibility to ensure that women and protected and supported so they can breastfeed their infants;
But, you are right, there are instances where infants/young children are not breastfed, and since the endorsement of the WHO/UNICEF Global Strategy for Infant and Young Child Feeding in 2002 by member states, there are clear criteria and standards to ensure safe and appropriate infant feeding practices. The Global strategy recommends that all efforts are exerted to support the mother and the child to breastfeed, or be supported with re lactation, wet nursing or donor breastmilk milk as long as accepted and respectful of the context. Infant formula is a recognized option that we need to consider when everything else has failed.
The IYCF-E Operational Guidance 2017 does provide a detailed set of recommendations on what type of support and the approaches to take when a child is not breastfed
https://www.ennonline.net/attachments/3127/Ops-G_English_04Mar2019_WEB.pdf
Action 5 of the OG-IFE, provides concrete recommendations on how we can protect and support women to breastfeed, and Action 6 provides standards and recommendations when artificial feeding is the only option.
Thanks and I hope this helps