The interchange fee differences between credit card types are not very high, usually around 0.5%. You can see the public Visa interchange rates at https://usa.visa.com/content/dam/VCOM/download/merchants/vis.... Credit card companies play a lot of games with this too and will “upgrade” your card type if they think it’s worth it, even if you don’t make any changes.

The biggest variances involve non-exempt (Durbin amendment) debit cards.