Why are some credit card companies(Discover, MasterCard, etc.) not accepted everywhere but others are(Visa)?

If you use credit for purchase, there is a processing fee charged to the retailer by VISA, MC, DS, and AMEX. It's a hidden cost you don't see and that's why companies prefer cash to credit. It increases their profit margin.

VISA has the lowest processing fees (1.5-3%). AMEX usually has the highest.

One more factor to consider: Discover is a "latecomer" in terms of credit cards.

Visa was actually started as BankAmericaCard, in 1966, and that evolved into VISA, and a separate group of banks banded together to form ICA, which eventually became MasterCard, also in 1966.

Discover Card wasn't released until the 1986 (debuted at the SuperBowl), and Amex didn't come up with a "credit card" until 1987.

The more correct statement is, Visa, MasterCard, Discover and American Express are payment networks that clear payments for credit card purchases where the merchant is a member of that network and accepts those cards,

Visa, MC, Discover and AMEX charge a percentage of the transaction as their handling fee, AMEX and Discover's fee tend to run higher than Visa and MC so merchants don't want to accept those cards as they eat into their profits,

According to Visa and MC, merchants are not allowed to charge a handling fee to use their logo'd cards,

No credit card is accepted everywhere. Visa is not accepted everywhere. Many places do not accept any credit cards.

Each place decides for itself which credit cards, if any, it will accept. If a place accepts Visa but not Discover, or Discover but not Visa, it is because that place decides to do that.

Each credit card company takes a percentage of the purchased item some take more than the others.

Because the credit card companies charge a fee where they are used. So smaller businesses like your local grocery store probably won't accept them because they can't support the cost it takes to do so.

I was about to ask this question too this morning