Not clear who said:
You know, Pete, I think you just hit the nail on the head. People
almost always refer to the distance difference 'if something goes
wrong, earth is only 3 days away.' That doesn't convince anybody but
the ninnies--and the ninnies aren't going to the moon either anyway!

I live on an island in the Caribbean. I often think this is good
practice for understanding the issues for living on the moon. With a
population of about 12,000 we don't have a CompUSA, Frys, Computer
World, etc. Paying high FedEx rates I can get something in 3 days
sometimes (1 or 2 for FedEx and 1 or 2 for customs) but most of the
time it takes about 2 weeks from when I order something to when I get
it. This means you always:
1) Have on hand a backup for everything
2) If your primary fails you order a new backup right away

As long as your backup does not fail in the first 2 weeks, you are ok.
In practice have very high reliability with this kind of strategy.

On the moon you can do a similar thing. On Mars you can not. If it
is going to take more than a year for spare parts, you just can't count
on any. The level of Engineering paranoia and faith it takes to design
for that is deadly.

The other big reasons the moon will be settled first a
1) You can amortize the cost of your tether over many
more flights per year
2) Can use a tether to the surface since no atmosphere and low
deltaV
3) Easy to setup 2-way tether traffic so much less energy input
-- Vince
spacetethers.com