How far can we detect lightning in radioastronomy? The wikipedia article on whistlers has this information:

Voyager 1 and 2 spacecraft detected whistler-like activity in the
vicinity of Jupiter known as &quot;Jovian Whistlers&quot;, implying the presence
of lightning there.

This surprised me, because this implicates a short range for detection of lightning, and I thougth atmospheric discharges produced a lot of radio noise, and so radiotelescopes on Earth should have picked signs of jovian lightning before the voyagers. As it seems not to be the case, what makes lightining hard to detect at distance?
Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, while radio telescopes work at 30 megahertz to 300 gigahertz.
Radio telescopes would need to be 1000x larger in order to resolve the direction of extraterrestrial whistlers.