This is why at work, we're encouraging and recommending to use some kind of SSO, but we're basing our cost off of the customers IDP.
Some "green" IDP like O365 OIDC, Okta, Entra and such are usually included without extra cost (and will be self-service soon, too). Some "yellow" - usually SAML - IDPs come at a fixed fee. We know them, we know they are weird, but we can deal with it.
Other things are flagged as red and call in hourly billed projects and recurring maintenance fees. Like, one customer has an in-house developed SAML IDP written in PHP a decade ago or so. I want our customers to use SSO, but that's a level of jank I'm not supporting for free.
Some "green" IDP like O365 OIDC, Okta, Entra and such are usually included without extra cost (and will be self-service soon, too). Some "yellow" - usually SAML - IDPs come at a fixed fee. We know them, we know they are weird, but we can deal with it.
Other things are flagged as red and call in hourly billed projects and recurring maintenance fees. Like, one customer has an in-house developed SAML IDP written in PHP a decade ago or so. I want our customers to use SSO, but that's a level of jank I'm not supporting for free.