sigh, i think some people need to read up on vexillology, or at
least go stare at a chart with all the countries' flags..
If you trace the origins and development of flags from ancient
times, several stuff came up from mismash of ideas from different
nations, as well as evolution in design of flags..
If you want to know, there are different types of flags - broad or
club pennant, civil flag, ensign...as well as flag etiquette, flag
conflicts, usage, divisions and charges...much of these, after
centuries of development, came up to be similar throughout the
whole world...mainly due to influence from one another..
Thats why we see most flags as rectangular 3 by 2, with or without
cantons, stripes and so on....or with just a unique coat of
arms.
Its no wonder Singapore flag look similar to other countries.
And there are flag families too, meaning similar looking flags are
classified under one family, like flags with Christian Cross, Union
Jack, The Stars and Stripes..as well as French Tricolore and
pan-Arab colours...
Coincidentally, Singapore one is classified under The Muslim
Crescent. If you think the intention is to appease neighbouring
Muslim countries, go ask Lee Kuan Yew or local
vexilologists.