Persons look for free work form home for the main reason because they are offered free of cost. But it should be kept in mind that all work opportunities on the net cannot be got free of cost as certain work from home opportunities might ask for an annual payment or monthly payment.
Even if a person obtains free work from home opportunity at certain point of time they might be required to pay some amount in order to generate huge earnings out of it. Normally free work from home programs might work well for a short term basis but for a long time residual earnings one need to shell at least certain amounts.
Unfortunately, many of the free work from home opportunities advertised on the internet turns out to illegitimate ones as they try to attract maximum number of persons. If searched properly it is possible to get free work from home jobs or opportunities.
The persons looking for such free work from home should do a little bit of homework, get references of persons who are already in to such kind of jobs, look for the authenticity of the website offering free work from home job and so on. Online forums too can provide some valuable information about these free works from home jobs.
Most free job opportunities websites will ask you to upgrade from free to premium.
I agree with you that along the way somehow a payment will be made.