How do you earn points with US based programs without a US credit card?

[settlement]

I don't understand

 

[andye]

Amex MR and Diners Rewards points transfer to SPG which offers access to AA, AS, UA (via Marriott).

Worthwhile Delta transfers are harder but reward inventory is possible through VA anyway

Diners transfer directly to AS but at lower rates than going through SPG first. However SPG won't be around forever so may become more relevant

AA has an online shop

Can credit car rentals to most

The hotel consolidators such as pointshound kaligo etc can credit to US airlines

Easy to buy AA and AS miles with regular offers

And there's flying:
Can credit OW to AA
Can credit Star Alliance to UA
Could credit Skyteam and VA to Delta (but probably not worthwhile)
Can credit QF CX BA and EK to AS

Suspect there are others