The eternal problem with companies like Tailscale (and Cloudflare, Google, etc. etc.) is that, by solving a problem with the modern internet which the internet should have been designed to solve by itself, like simple end-to-end secure connectivity, Tailscale becomes incentivized to keep the problem . What the internet would need is something like IPv6 with automatic encryption via IPsec, with PKI provided by DNSSEC.…
Last I checked, it hasn't solved DNS yet (there are unofficial projects trying to do that). I tested a small private network with a few devices and it worked very well.