We've seen the same with traditional volunteer community health workers. They are certainly overstretched and under compensated for their time. They also often are unable to keep in stock of needed treatments.
We recruit women that are invested in the community's health, but also receive motivation through selling of products like pro poor durables (cook stoves, water filters, solar), consumer goods (soaps, diapers, etc.), preventative measures (bed nets, water purification, clean delivery kits), and treatments (ACTs, ORS+zinc).
The margin on these products paired with routine monthly training refreshers keeps these women motivated over the long term. We essentially see our health promoters as 'retailers on the go'.