Why do wireless networks experience such a great reduction in actual throughput compared with their respective theoretical throughputs?

Wireless networks experience such a great reduction in actual throughput compared with their respective theoretical throughputs, because wireless networks experience a high number of collisions and require greater overhead on each transmission. The throughput varies significantly from the theoretical maximum speeds due to:

distance from the access point, physical obstructions, such as walls, signal-blocking or reflecting materials which affect signal propagation and reduce speed , interference - other wireless networks and devices in the same frequency in the same area affect performance and shared bandwidth - available bandwidth is shared between all users on the same wireless network.

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