I don't think there's any major programmatic difference that makes the autoinstallers work, they probably just avoid the common cr/lf, dos2unix, typos, etc. (read: user error). You'd remember when rlparker PM'ed a few of us asking why we thought people were having problems with the Wiki articles. The basic INI installation appeared clear & correct back then so I assumed user error and knocked up a php.ini and ioncube installer so we didn't have to rehash "How to install X" daily at the forum.
Lemme just go see what's there now...
If followed correctly the Wiki should get things rolling in regard to accessing a php.ini or installing ioncube, but the plethora of "installing custom PHP" scripts need editing to compile PHP correctly across all builds/servers. It could be done with one script yet last time I looked (8 months ago?) there were 5, and I just saw about 4 on one page just now (some of which are incredibly flawed in their build order) so can only assume there are now extra multiple copy/pasta goodies to further confuse the casual user and send them into fits of rage. Much of the info appears to be the blind leading the blind so users shouldn't look at it as a copy/pasta saviour, but rather as a rough guide on ways to get things done. They should absolutely not use some of those shell scripts.
ps. I facepalm when I read the Wiki so I don't look at it anymore
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How To Install PHP.INI / ionCube on DreamHost