There are many areas where utilities do not supply delta connections, and I'm not sure they exist at all outside the US.
Delta isn't used here in the U.K. for any sort of public domestic/commercial supply. All of our HV distribution is without neutral, so if a large industrial consumer has its own transformers and takes its supply at 11kV, then the xfmr primary will be delta-connected.
Once you get to the normal LV connections from the utility though, we really have only three distribution arrangements in use:
#1. Single-phase xfmr, 240V secondary with one side grounded, found almost exclusively in rural areas where the xfmr feeds just one or two isolated homes.
#2. Single-phase xfmr, 240/480V secondary, center-tap grounded as the neutral, 3-wire distribution. Fairly unusual, and again only found in rural areas. Individual homes are tapped for normal 2-wire 240V service, some from one side of the supply, some from the other. Farms etc. might get a 3-wire connection with load distributed between the two legs. Pretty rare, and really just a holdover from the past.
#3. 3-phase 4-wire wye secondary, 240/415V, grounded neutral. The standard distribution used just about everywhere except for isolated homes as described above. Even relatively small villages will have a sub-station which feeds a 3-ph 4-w network like this. Homes and light commercial are tapped for a 2-wire 240V supply while 3-phase users get a 4-wire wye 240/415V connection.
