Actually in the beginning Lao Tzu and Chuang Tzu period, the
teachings of Tao is a philosophy, Taoists then do not worship
deities and stuff. Lao Tzu is praised by many Buddhist masters,
including my own Master, and Master Han Shan. Lao Tzu is being seen
as an example of a Pratyekabuddha. Tao Te Ching is a work of 'Qing1
Jing4 Wu2 Wei2'.
But then, after Zhang Tian Shi/Zhang Daoling came to reform Taoism,
he brought along many other indigenous practices and deities, and
since then Taoism became the indigenous religion of China. Taoism
in Singapore IMHO is mostly into mediumship.
Nevertheless there are still some highly realised Taoists masters
now, according to my friend Thusness, who used to learn under one
such Taoist master more than a decade ago.
But anyway, just because Chinese folks practitioners worship Guan
Yin or Buddha along with other deities, that does not make it any
form of Buddhism. I think even if those Chinese folks practitioners
worship Jesus or Mother Mary, we also do not recognise them as
'Sinicized Christianity' or 'Sinicized Catholicism' 
