Por que o ss rotula as portas UDP como TCP?

Question

Todas as conexões UDP são prefixadas com TCP. Por quê?

$ ss -lunt
Netid State      Recv-Q Send-Q             Local Address:Port               Peer Address:Port 
tcp   UNCONN     0      0                              *:514                           *:*     
tcp   UNCONN     0      0                              *:68                            *:*     
tcp   UNCONN     0      0                      10.0.2.15:123                           *:*     
tcp   UNCONN     0      0                      127.0.0.1:123                           *:*     
tcp   UNCONN     0      0                              *:123                           *:*     
tcp   UNCONN     0      0                              *:5353                          *:*     
tcp   UNCONN     0      0                              *:53620                         *:*     
tcp   UNCONN     0      0                              *:59885                         *:*     
tcp   UNCONN     0      0                             :::514                          :::*     
tcp   UNCONN     0      0                             :::48693                        :::*     
tcp   UNCONN     0      0       fe80::a00:27ff:fe13:a1df:123                          :::*     
tcp   UNCONN     0      0                            ::1:123                          :::*     
tcp   UNCONN     0      0                             :::123                          :::*     
tcp   UNCONN     0      0                             :::56496                        :::*     
tcp   UNCONN     0      0                             :::5353                         :::*     
tcp   LISTEN     0      128                   127.0.22.1:22                            *:*     
tcp   LISTEN     0      128                   127.0.80.1:443                           *:*     
tcp   LISTEN     0      128                   127.0.80.1:80                            *:*