HID ballasts losses use to be between 5..20%, depends on the exact system. The simplest, cheapest and most efficent are series chokes, when the arc voltage is close to the half of the mains (for a stable arc the mains should not be lower than twice the arc, but the system needs room for lamp aging). That is, why the lower power HPS in the US/Canada market and pretty much all HIDs in the "230V" area are designed this way, with 55V arc for 120V HPS, 70..90V for "230V" area HPS, about 100..140V for "230V" MV and MH.
Then for lamps with higher arc voltage in the 120V area you need some form of step up transformer and these have vay more windings, so exhibit higher losses. And because of the more windings, they are heavier and more expensive. But the higher open circuit voltage allows the lamps to be more efficient, so these are the main choice for all but the low wattage HPS in the 120V world.
The more complex ballasts allow also designs with the ability to compensate for wider mains voltage fluctuation, which makes the installation mainly with longer wiring simpler, but it costs some extra losses in the ballast (generally the better the regulation, the higher the losses).
The LPS very difficult lamps to power in an efficient way. Unlikethe high pressure lamps, their anode column voltage drop is high from the first ionization, so if you add the high drop of the cold cathodes just after ignition, the ballast needs to beable to deliver quite significant power into a discharge with voltage drop many times higher than the normal operation (after electrode warmup). That means very high OCV requirement. And that means even on 230V, the ballast needs to be more complicated, so (unless some HF electronic gets involved) more lossy. So much the losses use to be in the 50..100% of the rated lamp power (so the ballast efficiency as low as 70..50%). In the latest years, electronic ignitors able to provide the higher voltage feed for the cold cathode stage operation made possible the LPS to suffice with a simple series choke ballast, then the efficiency became closer to the 70..80% (the LPS atill have rather low arc voltage, so the ballast losses remain higher). Of course completely HF electronic ballasts are able to boost the voltage for the cold cathode operation using resonance, so retain high efficiency for normal operation, but these came too late, when the LPS technology was already on the way out from the market, so there was no motivation anymkre to invest into their adoption.
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