Stripe is an ISO with First Data Merchant Services (FDMS, I believe now owned or controlled by Wells Fargo) doing the actual processing and, as such, assumes a different legal role than PayPal (which is a VAR for Paymentech).
The "two years testing their service" part is longer than a lot of ISO certifications, but that all depends. Ultimately, though, it's a lot easier to be certified as a VAR due to the fact that the processor (a bank usually, though can be an ISO) assumes more responsibility (risk/liability) in the relationship.
Regarding "forming better relationship with bank [sic]", it's not so much that one is has a better relationship than the other as it is their relationships are fundamentally different.
The "two years testing their service" part is longer than a lot of ISO certifications, but that all depends. Ultimately, though, it's a lot easier to be certified as a VAR due to the fact that the processor (a bank usually, though can be an ISO) assumes more responsibility (risk/liability) in the relationship.
Regarding "forming better relationship with bank [sic]", it's not so much that one is has a better relationship than the other as it is their relationships are fundamentally different.