Photoshop, Illustrator and similar graphic design software are in general bad at kerning. Why does the computer find it so hard that we need to manually go through headlines and text just to get it right?
Applications don't kern by default. The font files have internal kerning data. Application read the internal kerning data and display that. The cheaper the fonts, the worse the kerning tends to be.
Default kerning is a direct result of the font file and is not the fault of any application using that font.
Saying Adobe is bad at kerning does the software a disservice. Yes, as Scott said in his answer, lots of font files don't kern well by themselves. Fortunately, Adobe has the 'Optical' kerning option built into the Character palette:
Using this setting, the software will analyse the letterforms and come up with its own kerning. It's not always perfect, but it's a lot better than nothing at all.
edit: Word of caution, as per tim human's comment: be very careful with applying 'optical' when the font file already has decent kerning, it may make matters worse!
I worked at Adobe making fonts in the 80's and 90's. Back then, the kerning tables built into each font were painstakingly created by hand—or rather, by eye. We spent many hours looking at printed samples, marking and adjusting each letter pair.
Kerning by eye is an especially laborious process because of the optical interactions that naturally occur between letter pairs. When you kern one letter pair, the spacing of other letter pairs in the same word (or phrase) may suddenly look different. We'd spend as much time as the production schedule allowed tweaking and re-tweaking the kerning tables, knowing that they would never be perfect. Today's font makers almost certainly rely on automated kerning routines rather than the human eye to create the kerning tables that ship with their fonts. Unfortunately, this means more work for the discriminating designer.
First off, kerning and setting the "perfect" type is organic, and very subjective - what seems perfect to me might not work for you. As for programs being bad at kerning, I'll have to disagree. Let me (try to) explain.
Digital typesetting programs do not kern text by default. eg. in Photoshop, if you select the text layer and open the "Character" window, by default the kerning is set to 0.
Font files can have an embedded kerning table set by the type designer. As Scott said, if it is a cheap / free font, the kerning might be pretty bad (or completely absent even). To kern the text according to the type designer's table, set the kerning to "Metrics".
The other option you have (at least in Photoshop, and InDesign) is to set the kerning to "Optical". When set to optical, the program will evaluate the letterforms, and will kern the text automatically based on letter pairs. This may or may not be what you want, but it will more often than not be better than no kerning at all.
The "Optical" kerning is where the software does the kerning for you, and in my personal experience it is better than no kerning, and is comparable to the kerning embedded in the font file. That being said, you should, in my opinion, set it to Metrics to use the typeface as intended by the type designer (which is what I do as well, unless being used in a special context).