In Lithuania, the majority of mobile providers offer an end-to-end solution to their customers at €1 per month or less. This includes pay-as-you-go plans and is

In Lithuania, the majority of mobile providers offer an end-to-end solution to their customers at €1 per month or less. This includes pay-as-you-go plans and is likely to reflect the actual cost of this tech used on a large scale, given the significant adoption rate (which I estimate to be more than 5% of the Lithuanian population). To provide m-signature services, mobile carriers in Lithuania burn a client biometrics-linked key into the SIM cards they provide. This setup allows the use of phones with these special SIM cards for two-factor authentication, which can be considered three-factor with some caveats due to the inclusion of biometrics. The mobile signature technology has good UX where a user, while signing a document, usually enters their tax ID and phone number into a web form. They then react to a prompt on their phone by inputting one of two memorized PINs. It's easy, cheap, and secure. I also don't believe this technology is subsidized by the government. Though it's challenging to find specific legal language around subsidies for m-signatures, the price of this tech seems to be asymptotically approaching real costs through free market competition. In the Western world, a similar demand for electronic signatures exists. Although the market is currently dominated by costly certificate providers, they seem to lack moat, and it brings hope that this technology may be more widely adopted in places like the UK and US, once prices naturally fall. Lithuania is N=1 but it's an interesting case study for how mobile signatures can be made user-friendly (or at least "user-reasonable") and mass-adopted.