Not sure why the poster compared to AirDrop because it’s not really similar.
AirDrop works over WiFi and can send to nearby devices (using their radios to connect directly, even in the absence of a WiFi network). It can be used with strangers’ devices if they have theirs set to public mode — which has led to some unpleasant incidents as you can imagine.
Tailscale is primarily a private VPN network that you create only between your personal trusted devices, not strangers’. It works over the internet so it requires a working connection (of any kind). Its primary function is secure communication between your devices, for example you can do things like connect to services on your home server, assist a relative over remote desktop, use your home PC’s connection when you’re on hotel WiFi etc.
Tailscale is usually not something you keep going all the time but you can if you want, there’s no penalty for doing it. It only uses the encrypted tunnel when you connect to another of your Tailscale-enabled devices.
I guess you could stay connected to your Tailscale all the time just so you can drop stuff between your phone and PC for example but it seems a bit overkill.
It’s not hard to use btw, you just get their app, enroll it, and then it’s just an on/off switch.