Huge barriers of entry. In order to make a card product that is really competitive to Visa & Mastercard, it's a chicken and egg problem - you need on board both a lot of merchants (to make the product useful to customers), a lot of customers (to make the extra effort viable to merchants), and a lot of money (measured in billions, not millions) to get it started - even major tech companies like Ebay/Paypal and Stripe are too small to afford this kind of effort on their own.
If you make the product really attractive to merchants, then you will have a problem getting customers. You will have to compete with the existing credit card products. Banks make a lot of money on those existing products and are highly motivated to ensure that the product you propose never, ever gets off the ground. History shows that they are both willing and able to (a) use this money to "buy" customers over with bonuses that you won't be able to match because you aren't charging the merchants so much; and (b) aggressively try to keep you out of all the infrastructure - there are many 'moats' that they control, including the large settlement systems, technical infrastructure installed at merchants (forget about using the same POS terminals to read your cards and Visa/MC, even if it's technically easy), etc.
There have been and are many attempts to make new alternative card products, but they aren't realistic to succeed. EU considers a wish for such a card system every couple years, but it turns out to be unfeasible even given the combined financial resources of the interested governments. Right now Russia has a strong motivation to support and subsidize such a system, but again, they don't want it that much to warrant the huge expenses for the relatively low expectations of success.
If you make the product really attractive to merchants, then you will have a problem getting customers. You will have to compete with the existing credit card products. Banks make a lot of money on those existing products and are highly motivated to ensure that the product you propose never, ever gets off the ground. History shows that they are both willing and able to (a) use this money to "buy" customers over with bonuses that you won't be able to match because you aren't charging the merchants so much; and (b) aggressively try to keep you out of all the infrastructure - there are many 'moats' that they control, including the large settlement systems, technical infrastructure installed at merchants (forget about using the same POS terminals to read your cards and Visa/MC, even if it's technically easy), etc.
There have been and are many attempts to make new alternative card products, but they aren't realistic to succeed. EU considers a wish for such a card system every couple years, but it turns out to be unfeasible even given the combined financial resources of the interested governments. Right now Russia has a strong motivation to support and subsidize such a system, but again, they don't want it that much to warrant the huge expenses for the relatively low expectations of success.