Research Associate at the Centre for the Study of Existential Risk at the University of Cambridge
Thanks for this question MarcSerna.
Unfortunately, the lack of monitoring isn't limited to low-income countries, and even countries like the US struggle to maintain monitoring networks due to financial constraits (and changes in office). On increasing our monitoring capacity, the use of satellite technology is greatly enhancing our capabilities but we still have a long way to go for this to be a robust method. Often we must request satellites be flown over volcanoes, rather than it being routinely conducted and imagery can also be expensive. It should also be noted that volcanoes don't necessarily show signs of imminent activity. Some eruptions occur with minimal to no precursory activity (tremors, ground deformation etc.) so monitoring and prediction cannot always be a definite science.
One way that to be able to build our capacity for volcano monitoring would be through community empowerment, essentially building awareness within communities about how to identify signs of change at volcanoes and being able to report their concerns. Many citizen science projects are aiming to explore just this.
For now, I believe education and outreach with at-risk communities is essential to ensure preparedness of those most exposed. Certainly, my experience with the recent La Soufriere eruption in St Vincent was able to demonstrate the efficacy of long-term education programmes, resulting in no direct loss of life. Of course, dealing with disasters is multi-faceted and preparedness should also be directed at local authorities and stakeholders to ensure their preparedness to respond to a crisis. Again though, there is a severe funding source lack for these programmes and governments often do not prioritise this.