Are paid TLS certificate warranties actually worth anything?

Start with the actual warranty terms, not the dollar amount in the sales pitch. A certificate warranty may be intended to compensate an end user for a financial loss caused by a certificate authority's mistake when issuing a certificate. That is not necessarily protection for the site operator.

Check who can claim, what failure must have occurred, what losses qualify, the exclusions, and the claims process. A compromised server or leaked private key may be treated very differently from an issuance mistake. You can't assume the advertised amount covers either one.

Free certificates can do the TLS job just fine if they meet your technical and policy requirements. A higher price doesn't automatically mean stronger encryption or broader liability coverage.

I'd compare the products on validation type, automation, support, contract terms, and any regulatory or customer requirements. Then ask the paid provider for the warranty conditions and examples of what would qualify for a claim. Don't base the decision on an assumption that claims are never paid, or that they always will be.

There is a business reason to pay even if the warranty turns out to be narrow. Support and contractual commitments may matter when something goes wrong, particularly if you're managing certificates for customers. Those are separate questions from whether the warranty protects your company against a breach.

For internal services, a public certificate isn't the only option. You can automate certificate requests against an internal certificate authority if the devices using those services trust it. Public-facing services have a different trust requirement, so I'd separate those use cases before choosing a provider.

Don't overlook the automation tooling when assessing risk. A widely deployed ACME client could be a supply chain target, so review how it is installed, updated, and granted access. That's a different concern from the certificate warranty itself.