As an owner of a plug-in hybrid this is patently incorrect. Most electric car owners have at most of 240 volt outlet (in the US), which while can fill your battery in a few hours from home, still falls short of the half hour round trip to gas station and back. Maybe with time our infrastructure and technology will get to that point though.
For all the left people I know, including myself, The reason we don’t want a line drawn is because sometimes special circumstances arise. There may be medical complications in the third trimester that would result in the mother’s death and it’s not feasible to exhaustively list every scenario that could land her in this situation so it’s better to just not a put a limit on it so she doesn’t have some bullshit hoop to jump through later while she’s dying.
That said, I don’t think there’s anyone genuinely arguing that people should be allowed to get abortions super late into the pregnancy just for funsies. Third trimester is the logical cut off to me, and most of the people I know agree or want it slightly shorter. We just don’t want the law to specify that since it can cause legal complications. It’s better that it be considered a medical standard.