As already explained in the introduction, it is the working principle of electronic ballasts to generate a high frequency AC to feed the lamp. This technique is also applied in a steadily increasing number of so-called switch-mode power supplies, there to facilitate the use of a very much smaller transformer. This advantage comes more or less as a byproduct also to the electronic ballast because the principle of transforming at higher frequencies is the same. In most cases the complete ballast including the transformer and the conversion electronics has the same dimensions as an equivalent magnetic one but the weight is only one fifth (and thereby roughly reciprocal to the price).
As for CFLs, there is a wide span of final consumer prices. European high-price manufacturers claim that the cheap far-East products often do not match the European quality level, especially as cheap models mostly dispense with filament pre-heating. Pre-heating in principle excludes immediate start – this being a weak argument against pre-heating, since it takes barely one second. Dispensing with it cuts design and production costs, but it cuts lamp life heavily with increasing number of starts. Also the initial brightness reduction after cold start and the loss of luminous density at low temperatures and old age varies widely and may be more a problem of cheaper designs.