David Megginson wrote
In Canada, learning about temperature errors in the altimeter is a
standard part of the PPL curriculum, but I've noticed that it's not so
familiar to U.S. pilots (at least not private pilots).

I'm sure that Canada is the promised land as far as aviation education
goes, and that no instructor there ever sends a student to a checkride
when the student isn't REALLY ready to exercise ALL the privileges of
the certificate but is likely to be able to pass the flight test.
Unfortunately, this is not the case in the US. Nonetheless, altimeter
temperature errors ARE a part of the standard US private curriculum.

We have tables
in our AIP and other publications showing what errors to expect,

I'm sure that in this case you are referring to the ICAO Cold
Temperature Error Table, which is part of the AIM. Check it out
online:
http://www1.faa.gov/ATPubs/AIM/Chap7/aim0702.html#7-2-3

I don't know about you, but I have yet to meet a US flight instructor
who does not require his students to have a copy of the AIM and be
conversant with it. Thus I have to assume that every US student pilot
has seen this table at one time or another. It doesn't particularly
surprise me that many don't recall this. I'm sure you learned how to
extract a square root manually in primary school, as did everyone
else. Can you still do it? Maybe. But I assure you that not only
are most adults incapable of doing it, but that many will claim never
to have learned. Use it or lose it. For most private flying in the
continental US, altimeter errors are not particularly relevant.

and
when flying IFR, we are required to add those errors to all instrument
approach altitudes (MDA, DH, etc.) in very cold temperatures.

See, that's the basic difference. We are not REQUIRED to do anything
about those tables. The information is made available to us, along
with a recommendation to adjust minima as appropriate. It is part of
the AIM, which every private pilot candidate is expected to become
familiar with. How we choose to use the information is up to us.

The altimeter errors are very real - but a correction to MDA or DH is
not always necessary. For example, many ILS approaches are equipped
with a middle marker. The marker is not affected by altimeter errors.
It's not really the MAP, but in most cases it's close enough that it
can be used to signal a missed approach in situations where the
altimeter is suspected of reading high. Let's not forget that the
worst case temperature error at 200 ft and -50C is only 60 ft, while
altimeters can be up to 75 ft off in some cases and still be legal for
IFR use. There used to be a DH penalty for an inop middle marker
(either at the transmitter or receiver end) but this penalty no longer
applies. All this ignores the possibility that the pilost has a RADAR
altimeter available.

In the US, it is up to the pilot to decide whether in his particular
situation, given the available equipment and his skills, he should
adjust the minima as appropriate based on the expected temperature
error.

Michael