In general, why do capacitors have a higher tolerance than resistors?
Capacitor tolerances vary widely depending on the underlying technology.   

Resistor tolerances also CAN vary widely if inferior technologies are used, but these have largely been eliminated as not being cost effective or desirable and per-item trimming either mechanically or by LASER can be economic in some cases. 
"Composition" resistors were once common and had perhaps +/- 20% tolerance - worse sometimes. Long gone. Carbon film has tended to be replaced by metal film with better temperature stability and reliability. 

You can buy +/- 1% tolerance capacitors, and +100%/-50% tolerance capacitors. 


Electrolytic capacitors that rely on the surface area of an etched electride (eg "wet" aluminum) or a sintered electrode (eg Tantalum bead) depend on a mechanically inexact process to derive surface area and electrolyte thickness, and are accordingly hard to control tightly. 
Certain ceramic capacitors may have wide tolerances because the underlying dielectric properties are not temperature stable.
Plastic film capacitors can be +/- 5% tolerance and very stable dielectric materials such as polystyrene may allow +/- 1% tolerance capacitors to be offered.