>>83593506Ed is just too nice to fight back (normally). The episode where the eds wrestle with the kankers shows this when the kankers cant even hurt him but he doesn't attack because his mom said not to hit girls.
Ed is also shown to have a very high pain threshold and probably dose not mind getting "beat up" that much (though little things like a pebble in his show or Sarah's biting can agitate him).
That also explains why Ed fears girls like Sarah (who he thinks is annoying) and the kankers (who he thinks have the cooties) more than boys like Keven and Rolf.