An assumption of SETI is that we're listening for slightly older civilizations which would use much more energy (many orders of magnitude more). And it's a quite reasonable assumption.
Responding would be possible, if we knew the direction - a focused beam in direction of a specific star can be a billion times stronger than our "leakage", but we can't transmit to all stars, or 1% of all stars, or 0.01% of all stars - there are just too many of them.
Responding would be possible, if we knew the direction - a focused beam in direction of a specific star can be a billion times stronger than our "leakage", but we can't transmit to all stars, or 1% of all stars, or 0.01% of all stars - there are just too many of them.