Re why was this story perpetuated if there is no basis?

I would counter:  Do Italian-Americans, Greek-Americans,
German-Americans, Polish-Americans, etc, etc., have the same stories of
name changing?   Maybe the question is, why did specifically Jewish
families tell this bubbe  mayse?   My own theory is that many immigrants
were met at the dock by relatives who already were here and established
enough to invite siblings or cousins from the old country.  And the
first thing they heard was that "in America the family name is ......" 
All my cousins assured me that "Faivasovich" must have been changed at
Ellis Island to Morris.  When thru Jewishgen I found out that
Faivasovich was on the manifest, our founding greatgrandfather was
operating a business in Chicago 2 yrs after arrival with the name
Faivasovich, our grandmother was married in 1897 with that maiden name,
and ONLY in the census of 1900 hundred did Morris appear and Faivasovich
disappear!  Still they had believed the bobbe mayse. My own theory is
that the change on arrival by immigration officials (half of whom were
naturalized citizens themselves and among them spoke 40 languages) was
the least embarrassing and simplest to tell the children when they
started to ask about their names.

Jules Levin

On 6/25/2020 9:36 AM, peter.cohen@... wrote:

Smoke pours from the ears of veteran genealogists when they hear “his
name was changed by the immigration authorities”. Numerous analyses of
the experience of immigrants through Ellis Island and Castle Garden
offer convincing evidence that US immigration authorities used ship’s
manifests and the landing card pinned to the immigrant’s clothing to
determine their name and did not change anyone’s name.

So, why is the “my grandfather told me his name was changed at Ellis
Island” so widespread?  Either an entire generation of immigrants
conspired to lie to their children about how their name changed, or
SOMETHING actually happened.

Consider the case of my grandfather, who arrived via Castle Garden in
1891. All I know for sure is that his name was KEMAK on the 1891
manifest and COHEN on his 1895 marriage certificate. The story my
uncle told me was “when they asked his name, he gave his full Hebrew
name, including HaKohain and they wrote down Cohen.” My uncle would
have heard this directly from his father, who was the actual
immigrant. So where does the story come from?

A possibility:

The day he arrived, my grandfather was 19 years old, alone in a
strange country, whose language and customs he did not know.  It seems
likely to me that, when he left the immigration hall, tired and
bewildered, he would have been relieved to find a helpful Yiddish
speaker from an immigrant aid society (perhaps HIAS?) outside the
building. That person would have given him advice and direction. Part
of that advice might have been “no one here can pronounce your name,
your name should be _______.” It could have been as simple as the aid
society person writing down the immigrant’s name in Roman letters, so
that the immigrant would know how to write it. (Note that the stories
often say “they wrote down…”  Wrote down where? Apparently, immigrants
left the customs hall with no documentation from the US government.
So, if their name was written down and given to them, someone other
than a government agent did the writing.)  In my grandfather's case,
the name KEMAK was easy enough to pronounce, so that would not be a
reason to change it.  I lean in the direction of someone writing his
name in English, based on his Hebrew name and not his civil name. I do
not know who that someone was, but it almost certainly was not a
representative of the US government.

While we think of our grandparents as worldly and wise, at 19 years
old, they would have been neither, and could easily make the false
assumption that the HIAS person had some kind of government authority.