Why use a foreign word?

Why use a foreign word?

From Media Indonesia

If we go from Blok M, South Jakarta, to downtown Kota and
vice-versa, we will find a traffic sign reading Khusus Busway
(Busway Only). This traffic sign has been put up since December.
The word "Busway" is also painted in giant font on the fast lane
of the road.

As I'm a good citizen and love my nation and language, I would
like to ask the Jakarta administration why the traffic sign uses
a foreign word. Will it lower the image of the Jakarta
administration, particularly the communications service, if the
Indonesian language is used instead?

ICI SETYO UTOMO, Jakarta