Cartography, essentially.

In other words, it's likely that the cables are laid all within a few feet of each other in some places, or bundled together. To show this as it appears would make the map look confusing and would not convey what it wants to show.

This is more of an infographic, or a network diagram.

And there is also more stylised version, with medieval style:

http://submarine-cable-map-2015.telegeography.com/

https://www.telegeography.com/telecom-maps/submarine-cable-m...

Nice rendering and the additional information on latency from Great Britain as the pseudo-scale and changes in lit fibre all nice additions.

Also the exact locations are sometimes kept secret to prevent sabotage.

Perhaps in Russia or China. In the UK and Europe there is a big effort to prevent accidental 'sabotage', usually from fishermen. KIS-ORCA[1] project has a very detailed GIS map for undersea infrastructure.

[1] http://www.kis-orca.eu/map#.VQg_jnysWSo