Many good answers here. I'd say tailscale is useful if you want an "actual" VPN - that is, a virtual network, which is private. You can have VM or rented server somewhere and use it for backups, a media library - and you can connect to it securely over tailscale VPN over 4/5G - and you can connect with your laptop on wifi etc. Maybe a backup box at a friends place, or maybe that server/vpn runs an instance of gitlab and/or a personal wiki etc.

Tailscale unfortunately uses user-space wireguard still - other than that I think it's a strict "value-add" on top of manually configuring wireguard.

The option to route traffic through an exit-node can also be useful (make your phone behave as if it connects through your corporate VPN, with the fixed IP address that your clients white-list for access, for example) - but it's not the primary usecase.

While "VPN Services" like Nord are really anonymizing internet access providers routers - and while technically using VPN-technology, they're not really enabling Virtual Private Networks in a meaningful way - it's just your computer, and their exit-node - a tiny network of two - and they don't have anything to talk about - the exit node doesn't run a web site or a service - it's just a router.