Have you heard brethren make this statement? Have you yourself made it? Having preached in more than one culture in two languages I have not found this to be true.
I met Antonio Wed. afternoon in the home of a Sister here in the Dominican Republic. He is an old family friend, although they had not really spent time with him in 15-20 years. He came to the capital seeking a visa to travel to the US and needed somewhere to stay for a week or so. Nino began talking with him about the Bible that morning and that night he was baptized. He has been in many churches, seeking the true church. When he finally found it Wed. he didn't delay his obedience.
Last night in a rural village (less than 300 population) 55 were present for a service at the house of one of the members. Around 25 of those were visitors, some of whom regularly visit. Although there had been a death in one family in the village that day, 25 were present to hear the Word of God. The church in El Mamon is growing, primarily because the brethren are working. Many in the village can't read or write, but they can listen to the Word preached or taught.
You may say, "But that's in a foreign country". True, but there are people where you live who are looking for the true church also--they're waiting for you to contact them. Could the difference be, not in the "audience" but rather in us as workers?