Fuses fuses fuses

Ok, this is about fuses

1- a standard Bussman fuse is UL approved. Are any "high end" fuses UL approved?

2- do any component manufacturers supply their gear with any of the usual suspects of high end fuses as opposed to a standard Bussman?

3- let's say fuses do make a difference. Given incoming power is AC, why could fuses be directional? 

Not meaning to light any fires here- 

thanks in advance