The government and the local authority want to ensure they get the right amount of tax and care home fees from everyone.
In cases where the Local Authority think you deliberately moved the interest in the assets to escape care home fees, they may apply to the court to transfer the property ownership to the spouse. Therefore they are set-up for family reasons rather than depravation.
Whether this application is successful depends on when the transfer was made, especially if the trust was made when the health of the partner meant needing care was likely.
The court will use its discretion to consider all the circumstances of the case. We would always advise against this type of trust if you or your partner were going into care imminently.