The municipal solid waste (MSW) management is one of the major issues on the planet, but it is also a potential major source of resources for circular economy. This paper covers recent technical-scientific advancements related to (i) the choice of the MSW collection system between single stream and systems relying on separate collection; (ii) the customer engagement in advanced MSW collection systems; and (iii) the role of the informal sector for sustainable MSW management systems in developing countries. The current opinion on these issues is that separate collection gives superior results, but it needs a strong customer commitment that can be primarily obtained through information and educational campaigns. For countries that are still developing their MSW management systems, the inclusion of the informal sector is considered essential for obtaining resilient and sustainable systems.