How do volume production manufacturers use contactless JTAG programming?
I've seen three approaches in the wild:


If there is enough space on the board, the standard layout for that CPU type is used (e.g. 14 pin ARM, or 10 pin Altera) with a standard thru-hole connector, and the traces to the connector are routed on the top. For development boards, the header is populated normally, and in production, the holes aren't drilled, leaving large round pads.
Companies that have a large number of different designs sometimes standardize internally, e.g. 1mm raster and a fixed distance from the board edge, so the same test jig can be reused.
Fully custom solution for a board. If you produce a million units or have a very complex layout, it may simply be cheaper to make a custom board with pogo pins than to change the layout of the mass-produced board.