In-house shredders require initial capital outlay, employee time, valuable office space, utilities and regular professional maintenance. They are slow, dusty and noisy. Furthermore, you are still faced with disposing of the residual waste. Incineration requires sorting of material as not all data types can be burned. Labor and transportation must be scheduled.
Security is compromised as the material travels in readable form.
Typically incinerators have limited access hours, require significant additional handling and it is awkward to view records being destroyed. Incineration is harmful to the environment, it pollutes. Some data types may be retained several weeks before destruction. You must trust the hauler, and his employees, to establish weight and to safeguard your confidentiality. Landfill material bulldozed in today could be uncovered next month or year as landfill configurations change.