The whole-sample long-run Marshallian own-price elasticity (-0.641, with expenditure elasticity 0.524 = the quoted 0.52) is the number the authors present as "our results" for electricity and benchmark against the literature; the urban/rural splits and the Table B1 Hicksian income-group rows (-1.132 to -0.247, endpoints repeated in the conclusions) are presented as heterogeneity analysis around this headline estimate, not as the central estimate. || "Our results of long-run elasticities with respect to expenditure and price of electricity are 0.52 and −0.64 respectively. Since this elasticity is below unity, income growth apparently results in a less than proportional increase in electricity demand." (p. 258, printed journal page)
Rosas-Flores, J. A. (2017): 'Elements for the development of public policies in the residential sector of Mexico based in the Energy Reform and the Energy Transition law.' Energy Policy, 104, 253-264.