The fees charged annually to maintain the trust and the expense of setting up the trust can be prohibitive in some cases.
The special needs child or adult has virtually no control over how the funds are disbursed. The trustee has complete control of the funds in the trust, placing the beneficiary in the position of asking the trustee for anything they need. When the beneficiary dies, Medicaid will demand reimbursement for any money used for the beneficiary, which can often zero out the trust account.