I think there is a misunderstanding with that. There are churches who do not require membership to partake of the sacraments. We have a couple at our church who aren't members but still take part in the life of the church. The only privilege they don't have is the right to vote.
The American ARPs seem to have a different rule:
"FORM OF GOVERNMENT
191
Amendment No. 5 effective June 15, 1982 (V, A.3)
CHAPTER V
A.
DEFINITION OF A CHURCH MEMBER
1. The communicant church member is one who has been baptized, who has made public his profession of faith in Jesus Christ and who has submitted his life to His Lordship and to the ministry of the Church. He is entitled to all the rights and privileges of the congregation, including the right to vote in congregational meetings, the right to hold office unless restricted by a minimum age limit set by the session,
the right to participate in the Sacrament of the Lord’s Supper, and the right to present his children for the Sacrament of Baptism."
And from the Directory for Worship:
"Those who have been baptized and have made profession of faith and have entered into communion with Christ in the visible Church shall be invited to participate... Those who are not members of the visible Church and others who should not partake of the sacrament may be invited to remain during the administration of the sacrament."
Perhaps you could point me to the current governing documents of the Canadian church so I might see how they differ.