Are there white filaments, that are not so translucent?
Most of the plastics used for filament are inherently transparent and largely colorless. Color is achieved by adding pigment. Translucent and transparent colors are easy, but opaque colors require large amounts of opaque pigments, and even then, their opacity has its limits - even with black filament!

You can probably find very opaque white filament, but beware - too much pigment will affect the raw properties of the filament itself, either in terms of print temperature or things like layer adhesion or stringing/clogging etc.