Why are the grow tents so small?

I'm looking for a grow tent but they all seem so small. I'm looking for one that will hold 4-6 auto flowering plants but I don't think a grow tent that is only 80cm x 80cm x 160 cm will hold that? Should I just make my own grow box?

thats plenty of room

I think the magic number for a tent that size is four plants, but you could probably squeeze six.

why buy a tent when you can slap some 1x4's and some visqueen together in seconds any size you want??

thats enough space, line some milk crates with polly and use them. you can aquire milk crates behind walmart at about 2 am