why varbinary instead of varchar

Please take a look at this table :

http://www.mediawiki.org/wiki/Manual:Logging_table

As you can see wikipedia use varbinary instead of varchar :

| log_type      | **varbinary**(32)       | NO   | MUL |                |
| log_action    | **varbinary**(32)       | NO   |     |                |
| log_timestamp | **binary**(14)          | NO   | MUL | 19700101000000 |
| log_user      | int(10) unsigned        | NO   | MUL | 0              |  
| log_user_text | **varbinary**(255)      |      |     |                |

All of these information are text , so why they save them as binary ?

They do this for all tables .