Dispatch Time Zone IDs

Why are there so many time zones? A time zone not only roughly represents an area and its position on Earth with regard to the "movement" of the Sun, but also contains daylight savings time (DST) information for particular areas. For example, the parts of United States observe DST, but Alaska, Hawaii, Arizona, and part of Indiana do not. The US observes DST at different dates than the European Union does. Countries in the southern hemisphere have DST during the "winter" months, if at all. Etc. So, while many of the time zone IDs here cover the same GMT offset, each ID uniquely represents a different set of time zone and DST rules.
 
Time Zone Areas
ID
(GMT) Greenwich Mean Time : Dublin, Edinburgh, Lisbon, London 0
(GMT) Casablanca, Monrovia 0.1
(GMT+01:00) Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna, Belgrade, Bratislava, Budapest, Ljubljana, Prague, Brussels, Copenhagen, Madrid, Paris, Vilnius, Sarajevo, Skopje, Sofija, Warsaw, Zagreb 1
(GMT+02:00) Athens, Istanbul, Minsk, Helsinki, Riga, Tallinn 2
(GMT+02:00) Bucharest 2.1
(GMT+02:00) Cairo 2.2
(GMT+02:00) Harare, Pretoria, Jerusalem 2.3
(GMT+03:00) Moscow, St. Petersburg, Volgograd 3
(GMT+03:00) Baghdad, Kuwait, Riyadh, Nairobi 3.1
(GMT+03:30) Tehran 3.5
(GMT+04:00) Abu Dhabi, Muscat, Baku, Tbilisi 4
(GMT+04:30) Kabul 4.5
(GMT+05:00) Ekaterinburg 5
(GMT+05:00) Islamabad, Karachi, Tashkent 5.1
(GMT+05:30) Bombay, Calcutta, Madras, New Delhi 5.5
(GMT+06:00) Astana, Almaty, Dhaka, Colombo 6
(GMT+07:00) Bangkok, Hanoi, Jakarta 7
(GMT+08:00) Beijing, Chongqing, Hong Kong, Urumqi, Perth, Singapore, Taipei 8
(GMT+09:00) Osaka, Sapporo, Tokyo, Seoul 9
(GMT+09:00) Yakutsk 9.1
(GMT+09:30) Adelaide 9.5
(GMT+09:30) Darwin 9.6
(GMT+10:00) Canberra, Melbourne, Sydney 10
(GMT+10:00) Guam, Port Moresby, Brisbane 10.1
(GMT+10:00) Vladivostok 10.2
(GMT+10:00) Hobart 10.3
(GMT+11:00) Magadan, Solomon Is., New Caledonia 11
(GMT+12:00) Auckland, Wellington 12
(GMT+12:00) Fiji, Kamchatka, Marshall Is. 12.1
(GMT-01:00) Azores, Cape Verde Is. -1
(GMT-02:00) Mid-Atlantic -2
(GMT-03:00) Brasilia -3
(GMT-03:00) Buenos Aires, Georgetown -3.1
(GMT-03:30) Newfoundland -3.5
(GMT-04:00) Atlantic Time (Canada) -4
(GMT-04:00) Caracas, La Paz -4.1
(GMT-04:00) Santiago -4.2
(GMT-05:00) Eastern Time (US & Canada) -5
(GMT-05:00) Bogota, Lima, Quito, Eastern Indiana (US) -5.1
(GMT-06:00) Central Time (US & Canada), Mexico City, Tegucigalpa -6
(GMT-06:00) Saskatchewan -6.1
(GMT-07:00) Mountain Time (US & Canada) -7
(GMT-07:00) Arizona -7.1
(GMT-08:00) Pacific Time (US & Canada); Tijuana -8
(GMT-09:00) Alaska -9
(GMT-10:00) Hawaii -10
(GMT-11:00) Midway Island, Samoa -11
(GMT-12:00) Eniwetok, Kwajalein -12