A virtue of a Lyric is that it stays on theme, doesn't just Rhyme for the sake of Rhyme, with Lines full of words that don't maintain a coherence of theme, just manage to 'land' on the Rhyme-word.
You stay on theme with this one.
It is difficult to write Song with a philosophical message. For me, they seldom 'work'. There's too much reality to have to account for. Almost every Line, if it rings true, also demands context, gets context from the reality we know, which sometimes contests the philosophical allegations.
I'm not sure you intended to question the grandfather's belief in the mythical allegations, or that the Singer-Character had begun to question them, after his grandfather passed away, as indicated in the Refrain-Type Chorus, the Line ending Verses I and II, and, with a variation, Verse III.
Note that the actual 'execution' of a Song, the singing of the Lyric to a Melody, can bring a Lyric up in entertainment value. If this Song could provoke a lot of discussion that could be another point of merit.
Presenting a Lyric on the written page, for a reader, can have a different effect than 'consuming' a Lyric by hearing the words sung.

TITLE: "Grandpa Used To Say"

Verse I:
We don't burn books in America! (Book-banning is in the news right now. We DO burn books. A meme says: The people who burn books are never the good guys.)
In God we trust; That's our way! (The Nazi Party, in command of the German Army, had 'God With Us' on their belt buckles.)
Children don't go hungry in America! (One in five or six American children goes to bed hungry, comes to school hungry, goes home, hungry.)
Is that just something I remember, (Yes, it was the mythical America we thought we lived in.)
my Grandpa Used To Say?

Verse II:
We don't put tax on taxes! (Social Security deductions from every paycheck earned in a working lifetime, deducted after Taxes, paid into the Federal Insurance Contributions Act (FICA) can be Taxed again, as it is paid back to you in retirement.)
In America we don't do things that way! (You mention the phonebill. Jeff Bezos made $10 billion dollars in 2018, net, not gross, and didn't pay a dime of Taxes. Only the poor and middle class still pay Taxes. Those rich people who own, those rich companies who got all those Tax Cuts, who are inflating the price of everything they sell, don't pay Taxes any more. They still get 'refunds', if that's the right word, and subsidies, and immediate loan forgiveness.)
There's death before dishonor for an American!
Is that just some thing I remember,
my Grandpa Used To Say?

Bridge
He talked about a war that made heroes out of men, (How men behave in war is often not heroic.)
a thing called The Depression; you know he mentioned that now and again. (October 1929; banking practices, Predatory Lending, collapsed the global economy. 1933 Glass-Steagall Act prohibits Professional Lenders from writing Mortgage Documents with built in Foreclosure clauses, and getting Amateur Borrowers to sign them, legally committing to cooperate when the Foreclosure happened. 1993, Glass-Steagall is repealed. Bankers become banksters, again, and by 2008, Predatory Lending collapses the global economy again. A Great Recession, the media and politicians call it, to keep from panicking the public, but it is, as gauged by financial losses and economic disruption, a Great Depression, on a global scale.)
It wasn't the fever! He was just a dying breed! (For most of that generation, called America's Greatest Generation, it was never revealed to them that their mythical America was not real. They are a dying breed, taking their memories of realities with them. Talk to them if you know them. See what they tell you of what they knew or believed.)
He's resting in peace now in the land of the free. (There's a report out on loss of Freedom around the world, country by country. America is listed as losing 18%, I think, of its Freedom since 2011, or some recent date.)

Verse 3
You know a man is worth his gold in America,
as.long as he can keep things his way. (lomg - long) ('worth his gold'? 'as long as...' As long as he believes in the myth? I'm not sure what this Line hopes to say.)
You never ride a fence; always work for your pay!
That's (just) a few things I remember my Grandpa Used To Say. (Singer-Character says 'just' in VI and VII. Leaving it out in VIII could indicate the Singer-Character hasn't decided about whether Grandpa's America was mythical. Having it in the Line doesn't necessarily mean he's (or she's; a female singer for this Lyric might have a powerful effect) made that decision yet, or, depending on the listener's point of view, that he/she has.

You know old gramps, he sure loved that gold ole usa. (gold or good? Gold could have meaning so I'm not assuming you meant good.)

There will always be another song to be written. Someone will write it. Why not you? www.garyeandrews.com