I disagree with British. There are specific indications for both. If one doesn't travel, they probably aren't needed. You can read detailed indications on the CDC web site. In summary, Typhoid is strictly a food or water-borne illness. Hep A is similar, but also indicated for IV drug users and those involved in gay sex.
Hep B is 3 injections. Children get it routinely now as part of their vaccination schedule. Hep B can be easily caught in any US hospital. It’s much easier to pick up than HIV. Be safe, not sorry.
I am going on the Nov 2 trip. I have had the hepatitis vaccines, which are recommended for a lot of travel, and I have had the typhoid vaccines twice before for trips to China, but the second one might have made me sick (or maybe it was a coincidence). So I have not gotten typhoid for this trip. I am not really worried about typhoid on this trip. Actually not really worried about hepatitis on this trip either. But I would recommend HepA/B vaccine as it is easy. But start early as the others have said.
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I had both done for a previous trip (China). The CDC does recommend both for Argentina: https://wwwnc.cdc.gov/travel/destinations/traveler/none/argentina
If you're travelling soon, you won't be fully covered against Hep A as it requires 2 injections, 6 months apart.