As John Robb notes, a key issue in Ukraine and elsewhere (including Venezuela, Thailand, and perhaps Turkey again) is the easy which an open source insurgency may be started and continued. If the 20th century and earlier history had the classic dichotomy of haves vs. have-nots, than perhaps the 21st might be the haves vs. the would-earns.
In this case, the underclass is comprised of people simply yearning for an honest day's work, a chance to perform a trade or profession without much interference from the power elites. However, many of the "power elites" are individually not that powerful themselves. The system/organization that employs them restricts their ability to use their individual judgment in certain situations, perhaps compounded by group-think and institutional bias. For example, a corrupt cop shaking down bribes may be given a blind eye (if not encouraged for a cut) by his cash-strapped superiors. However, an individual still effectively set an example that sparked a series of revolts. A fruit vendor burning himself in protest started the Arab Spring.
Even with tools like sock puppet accounts, online censorship/manipulation (even if subtle rather than overt), and plain spinning are deployed (and I believe they were in many such cases), there comes a point where a situation can no longer be contained. In the developed countries, there is less desperation (for now), allowing much of the systems to continue to function. In more desperate circumstances, even a humble fruit salesman or bulldozer operator can help topple a regime.