qaq parent
I had e-com store as a student in late 90s they processed em fine
I think any experience of the late 90's is no longer applicable today, banks have learned the hard way that high risk transactions and card not present transactions are not something that they have the expertise to deal with when the scope is global rather than local.
They'll just connect you with Stripe, authorize.net, braintree or some other IPSP.
Really, I don't see what this contributes to the discussion, I would assume that if the OP was able to sign up for their own merchant account they would have done so. To process six figure sums on someone else's merchant account is usually for a reason other than convenience because the fees are high enough that you will want to cut out that particular middle man as soon as possible.
Your merchant account can be with your bank and you just use authoriz.net as a gateway. Fees might be a bit higher than stripe but in case of problems you can talk to a human and resolve your problems.
I've been in that position for many, many years and not a single time has my bank been useful to me. The gateway people usually are able to help out, depending on what the issue is. And this across a multitude of banks.
And yes, it's a better solution than Stripe, assuming you are not a high risk merchant, in which case banks won't touch you.