Less straightforward than you'd think. Ideally, it'd just be a matter of a text or call and having them input a code, but the costs lie in the failure state: we already deal with a large number of ccTLD registries, and many of those, including the IEDR (.ie) who we deal with regularly, require some form of documentation to allow domains to be registered, contacts to be updated, &c. Even with a 30% gross margin on .ie domains, the support costs with a highly automated application documentation submission process are high enough that we don't actually make much money on two-year registrations until the first renewal.

Thankfully, the new requirements for gTLDs aren't quite that onerous: we have to contact them to validate phone numbers and emails (which can mostly be automated), and we only have to ensure that the address provided is valid. That said, the costs involved in address verification aren't small, and we're hedging potential savings in avoiding fraudulent customers against the additional costs involved.

ICANN can't push back against the LEAs though: this stuff is now in the contract, so we're all stuck with it.