Why is inherent risk for the existence assertion for accounts receivable often set higher than inherent risk

Question:

Why is inherent risk for the existence assertion for accounts receivable often set higher than inherent risk for the completeness assertion?

Accounts Receivable
Accounts receivables are debts owed to your company, usually from sales on credit. Accounts receivable is business asset, the sum of the money owed to you by customers who haven’t paid.The standard procedure in business-to-business sales is that...