From an end user perspective, Paypal is a service which magically sends money over the Internet, and you're near-permanently logged into it, so you can pay for anything with almost no friction after you use it for the first time. A Stripe dialog is just a form/modal you see on a website asking you for your credit card details.

They're similar services when you break them down, but Paypal is almost more like a social network for users, with accounts people may re-use dozens or hundreds of times over a year to pay for things. Many end users probably have no clue what Stripe is and just see a generic Web 3.0-looking credit card form (probably ignoring reassurances about how the merchant website doesn't actually receive the card data; that stuff goes over many people's heads, or they just don't even notice it).

IIRC stripe checkout remembers login info.

In that case I might be wrong. I've only ever used Stripe as an end user, and each time I used it it just appeared to be a credit card form, with no accounts and no memory of previous credit cards I've entered (which is what I would want anyway).

While it's similar, I think there's hesitation since the customer might not know that it's similar in this regard.

Plus the act of re-entering the credit card number and/or not being able to use a recurring PayPal balance to pay off something might be a non-starter for some.

Maybe with the new checkout, which seems to use dedicated domain.

If I remember right, the older checkouts were hosted on vendor's website -- and you would not know if the cc info really goes to stripe only, or if vendor grabs a copy as well.

Not really, how does the end user know that the credit card number they're entering isn't being stolen by the merchant they're buying from? In theory the merchant should never even get the credit card number if they're integrating with stripe honestly and correctly, but the end user won't know that unless they're inspecting the traffic.