The biggest players in the bond market are either exempt (they're a pension fund, a 401(k), a foreign entity, a university endowment, a charitable organization, a church or other kind of non-profit) or pass-through (mutual fund, ETF).

I recommend Ken Fisher's "Debunkery" which covers a lot of economic what-ifs with hard data. Capital gains tax rates and treatment varied widely throughout the US history, yet collected revenues did not.