Inner reflection

So i am aware that the point of call for inside to be made white to maximize reflection of light but as far as I've seen everybody looks like they using silver , like from foil, how so ? Something I dnt know about ?

The foil type is mylar sheet which is very good stuff, but matt white paint is just as effective and cheaper.

Many of us use mylar tents, but as said above if paint is an option its much cheaper and easier.