With regard to how one would have been informed of the US taxation policy in times gone by: I just looked at my old US passport, issued in 1972 when I first went to the UK and also the one I was using when we married -- and there is nothing in there about taxation. I haven't yet gone through them all to find out when they did start adding that note.
I’ve decided it’s time to put away the Christmas decorations, so whilst I was in the loft/place where the water tanks are/attic I rummaged through the files and found my old passports. I also found the letter informing me of ILR. It was from (the) IND.
The oldest passport was issued in 1976 (the large bi-centennial collector’s edition). It states:
1. I cannot travel to Cambodia, Cuba, North Korea, North Vietnam, and South Vietnam. Funny how times had changed. In 1968 the US Army offered me a free, all expenses paid tour of South Vietnam with no requirement of a passport.
2. Loss of Nationality if I took an oath to a foreign state.
3. A Warning to Dual Nationals.
4. For the Treasury: a note that I could not import goods of Southern Rhodesian origin, in addition to the above. But not a word about US taxes.
The next passport was issued in 1981. It states:
1. As above, but there was no longer a ‘Warning’ to dual nationals.
2. And still not a dicky bird about US taxes.
The next passport was issued in 1986 (for 10 years!). It states:
1. As above, but no more Rhodesia. It was replaced by goods of Nicaraguan origin.
2. Still no word on US taxes.
The next passport was issued in 1996. It states:
1. Nicaraguan goods have been replaced by Libyan, Iraqi, Yugoslav, Haitian, and Iranian goods.
2. A whole, dedicated paragraph concerning the IRS, and the requirement to file US taxes for those resident abroad.
So, no excuses from 1996 onwards at least.