LIGHTING is a very short-lived phenomenon. A hundred years ago we didn't have "city lights" at all and what we did have were gas-powered and probably wouldn't have showed up in local orbit, let alone a distant galaxy. A hundred years from now, when we would have had to repair *everything* that currently exists on the roads several times over, not to mention thousands of building regulations, and you probably *won't* have lights visible from the sky.
If they think reflected shine from the Sun on the planet's face is hard to detect, how do you intend to detect a "light pollution aware" civilisation (we ourselves are still doing things like turning off streetlights in tests, fighting energy-saving bulbs, making sure that useful light is focused only on the lit subject and not random sky etc.) against all the others.
And two hundred years, hell, call it a thousand, is a tiny, insignificant portion of a race's evolution, especially on astronomical scales. Most of the places we look, the light takes longer than that to get to us, so if we spotted a civilisation just at the peak of its energy production, they've probably been long dead anyway and we'd never be able to see anything more interesting of them. Hell, if we invented a faster-than-light ship, zoomed over to them using all the money and production capacity we have, they'd be finished in it by the time we got there and outrank even us.
That's not to say that detecting a civilisation wouldn't be huge news - but detecting them off the tiny amount of light beamed from their planet into space for literally fractions of an astronomical second isn't really a sensible way to find them. Better to look for the civilisation that came a thousand years after them and who were able to modify planetary orbits etc. that are millions of times easier to detect.