I think the title should include "countries with cheap medical" care, instead of "developing countries". Clearly, OP means that one might be able to manage without insurance ion countries where medical care is so cheap that one could pay out of one's pocket.

But not all care is cheap. If one needs medical evacuation, or lengthy hospital stay, care can be quite expensive. What of you need a family member to come and help you out during your recovery?

On a week long trip, I met two people who were involved in accidents in Vietnam. One was trying out a rental motorbike when the bike went out of control, resulting in a broken ankle. Another was hit by a motorbike walking. She was in the hospital for 3-4 weeks. She wasn't able to communicate with the doctors in Vietnam effectively. They kept on doing their own thing, completely ignoring her complaints. She got better care when she was able to travel to Bangkok. After 4 weeks, she was still on crutches and needed a wheel chair to negotiate the airports, BKK and NRT.