So far its still pretty tough to spot an earth similar mass rocky planet in the habitable zone.
If someone were looking for earth by the transit method they would have to be in line with us, spot the 12 hour transit, wait 365 days and spot the transit again.
For all the large and close orbit planets we’ve found, there must be thousands more in our galactic neighborhood that we can’t see yet. That’s not counting potentially habitable moons orbiting large planets.
True, as of now, we can mainly only detect planets that are much larger and/or much more massive than the Earth. There may also be lots of "stray" planets not orbiting any star: planets that were 'kicked out' of their original star systems via gravitational encounters with other stars or planets. Like Earth, they may be massive enough to have a molten core and therefore be able to generate their own energy to support life. Life something like we have around deep sea vents, although that life likely didn't originate there.