All email processing jobs are scam

i have come across many email processing jobs and all of them are scam.On most of these sites its stated that you can earn 15-25$ per processing  emails of big companies,why would the company want to hire you when they have  automated email processing programs which don't cost a cent and all of these email processing jobs require you to buy their package or e book to get started.Once you have bought the package you may be asked to post ads  through ad sense  and according to them when some one clicks on the ads  you will get commission but they forget to mention that posting an ad on ad sense will cost you money.sometimes they may ask you to send email to certain addresses(which is considered scam). one thing is certain of all these sites that you don't get paid.