That's easy – they're formulated to kill insects, not arachnids. Most household "bug sprays" will sooner or later kill any spider that's directly sprayed, but have little residual effect against spiders that come by later.

Does raid fly spray kill spiders?

Raid Multi Insect Killer, Kills Ants, Spiders, Roaches and Flies, For Indoor and Outdoor use, Orange Breeze, 15 Oz.

Can fly and wasp killer kill spiders?

Swat the Spiders

Spiders can sometimes be killed with a fly swatter, but these creatures are sturdier than insects, with a hard exoskeleton that resists light blows.