Can someone who writes server side data base and related software please explain something to me?

Why is it that so many web applications will not accept names with hyphens "-" or periods "." or apostrophes " ' " in them. There are other characters that are common in people's names, but I'm primarily interested in those that are English language oriented. In addition to why please offer data base or similar code fragments, or web addresses for examples, that program around these issues.

Some examples:
Mary Reese-Jones
William St.Paul
Seamus O'Malley
(This names were fabricated for this posting. Any similarity to real persons is accidental and coincidental.)

In most cases, the names get squished into one long string:
Reesejones,
Stpaul,
Omalley

In other cases, the names become two parts, as:
Reese Jones,
St Paul, and
O Malley.
This implementation really confuses things when there is also a middle initial as:
Mary E Reese Jones,
William D St Paul, or
Seamus M O Malley.

I remember from COBOL that names were 'alpha' not 'character' data, but those days are gone with eight+three file names. I don't see a bona fide justification for this absurd application behavior other than something loose between the programmer's ears.

Comments?
~~~ 0;-/ Dan

I will provide one possible explanation but I will let you search the web to find out the rest of the information you seek. Removing special characters is one method to mitigate SQL injection attacks, albeit not a good one.