Duh! I thought nobody would try that except a 13-year-old.
I have had three aides in recent years who did it this way (plus my daughter, once) and it was all I could do to keep from going ballistic.
The practice may not have originated in Mexico, but it is common with people from there. The theory is that water is so precious and needs to be brought in (in buckets) and therefore, the dishes don’t get really clean.
Sponge them off, then try to rinse in progressively soapy water. This is America and my water is included in my rent so DO NOT wash dishes this way!