> Ascribing it to “economic conditions” blinks reality.
No, it reflects well-established reality.
> Americans are economically better off now than they were in the 1960s, when TFR was much higher.
Yes, exactly. Globally, on a by-nation level, prosperity in general and social safety nets in particular, as well as access to birth control, are close and immediate drivers of reduced fertility. When family is your only old-age, disability, or unemployment support network, the economic incentive to have a large family is greater. When those are socially provided, raising children is a cost without as much of an economic purpose.
> But Muslim Americans, who are also wealthy and educated, have a much higher TFR than whites and other Asians.
Muslims in the USA are not more educated than the general population, having college degrees at about the same rate as the general population (31% in 2017, vs. 34.2% for the general population). [0][1] They also aren’t more affluent, being similarly likely to have an income over $100,000 but more likely to have an income under $30,000 than the general population. [0] Also, Muslims aren’t categorically Asians or categorically non-White (in fact, more are White than Asian, racially [0]), so you should either not use “other” for either racial category or should use “other” for both; the non-parallel use suggests you think Muslims are categorically a racial subgroup of Asians.
[0] https://www.pewresearch.org/religion/2017/07/26/demographic-...
[1] https://www.statista.com/statistics/184260/educational-attai...