I'm presently building a solution to programmatically build, view, and validate HTML forms when I came across the ol' PHP non-scalar form variable handling problem. Because my form validator class would really have no way of knowing if a given form variable was meant to be scalar or not, I decided to TREAT ALL PHP FORM VARIABLES AS ARRAYS, i.e., to use the '' syntax for all variables, scalar or not. This way, the form designer need not remember to specify the '' syntax, and the Form->HTML transformer need not scan for every input within the form, looking for duplicate names. This also eliminates the risk of losing data you meant to keep in an array but to which you forgot to apply the '' syntax.
You may then either treat all form variables as arrays in your form handling code, or you may, as I intend to do, filter each HTML request through a Front Controller (desc. in Fowler, PoEAA). The Front Controller would convert all arrays of length 1 to a scalar variable and leave multi-element arrays as they are. This should essentially convert PHP's handling of non-scalar form variables to that of ASP's (or slightly better, since multiple form values of the same name will actually be arrays, not just comma-seperated values).
This way my Form Validator class can just check if the input to validate is an array, and then apply some constraint across each element in the array.