There are a few more positive aspects to travel by bus. As well as some other drawbacks.
Positives that I forgot:
1) I don't have to worry about macho drivers who are ticked off because I am "driving while female.
2) If there is a flat tire or mechanical breakdown (and there were none during the past 20 days), I don't have to fix it. It's someone else's problem.
3) No money spent on auto repairs.
4) No time spent searching for replacement parts for a Mazda (not the most common make of car in Guatemala and consequently, when I am in remote rural areas, it's not always possible to find parts).
5) No waiting for parts to be ordered, repairs to be completed.
And then some other drawbacks:
1) Comfort. Or the lack thereof.
2) Being the only person like me on the bus and therefore sometimes the object of scrutiny. This is actually a kind of neutral observation, not really positive or negative.
3) Being jostled around when the driver makes some wild maneuvers.
4) While I have been very lucky in my bus travels, it seems that a fair amount of the highway accidents that you read about in the newspaper involve buses.