Many cabins in the mountains in Norway use thick plastic bags that you just tie off and dump in a skip when you leave. At least they did last time I rented one twenty years ago, so the general idea is not new. Sealing the waste in with a biodegradable film is a neat idea though and makes a lot of sense for a hot climate.
The challenges of developing nations aren't technological, they are poor infrastructure or organizational.
It's been said... building a toilet is easy. Keeping it clean and operational for years is hard.