There are a number of things.
1. Foreign Policy and SA's love for China/Iran/Terrorism groups and then the Minority persecution driven by laws and policy
2. Trade Defecit which SA obv likes , but the usa doesnt
2. MAGA and his election promises
Like it or not from a USA pov the tarriff thing is exactly what he promised in his election manifesto.
It is coming back to MAGA. He wants manufacturing to move back to USA. With 30% it does not make sense to manufacture cars amoungst other in SA. It make mroe sense to shut down here and expand / open factories in USA.
Unemployment is allready down in USA. proving what he is doing is right from his pov.