Why don't TLDs resolve?

There are no address records stored for these domains. However, as there is an address record stored for to. (see below), I guess it solely depends on the particular policies.

http://ydal.de/a-records-on-top-level-domains/ gives a very nice overview over http servers running on hosts various TLDs resolve to.

to. resolves to 216.74.32.107

$ dig to

; <<>> DiG 9.7.3 <<>> to
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 55583
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;to.                            IN      A

;; ANSWER SECTION:
to.                     43186   IN      A       216.74.32.107

;; Query time: 1 msec
;; SERVER: 192.168.178.1#53(192.168.178.1)
;; WHEN: Sun Dec  4 18:57:17 2011
;; MSG SIZE  rcvd: 36