Whether these efficiencies are politically feasible is another matter; because as with soil the substantial barriers are political and economic. Tax subsidies provide water to people and industries in the absence of "real cost pricing" that encourage wastefulness (Postel, 1992a: 2333). With water made so cheap governments, there is no real incentive for growers to invest in more efficient systems. Moreover, as noted, the ability of nations to invest in technologies and conservation varies considerably.