The follow are some reasons why TEC prefers not to support single women missionaries. These are brief headings rather than addressing every possible exception.
Under normal circumstances, God’s Word reveals that a woman is under her father or then her husband. So it is desirable for her to be connected and in a position of following rather than leading. This is a family/household/authority concern.
There is no example of a woman traveling or ministering on her own in God’s Word. Certainly there were ladies who supported Jesus’ ministry, and Paul referred to ladies in Philippians 4:3 as laboring “side by side with me.” But these are all “with” not “by herself.”
It is generally true that women are more vulnerable, and, depending on the field/assignment, a woman could face greater physical (and even legal) dangers, not just on the field but even just traveling to it. God’s Word refers to women as “weaker vessels,” which does imply a higher value (so it’s not devaluing), it would also require “extra” provision and protection. This is a physical concern.
Of course women have been and are currently used by God in many situations, for which we can be thankful. Not every situation is the same, not everything can be ideal.
And yet, as one local body we only have so many resources to put toward outreach. So, in light of the above, and in light of our limitations in both attention and finances, we prefer to support men and their families. We hope this sets an example for both the young men and young women in the church. This is a practical concern.