the lemonade could be pressed and processed in a kitchen where meat is prepared and surfaces are improperly cleaned. also in most cases, we are talking about children who might not be fastidious about thorough handwashing.
would E. Coli or Salmonella thrive and multiply well in low pH / high sucrose cooled liquid culture? no. however, many organisms would remain viable. i have worked with strains of 0113 and 0157:H7 that have extremely low infectious doses; in some cases, the infectious dose is one organism.
also, norovirus (stomach "flu" / viral gastroenteritis) is efficiently transferred though food preparation by someone who is infected.
do i think cops should go around busting lemonade stands? no. however, i'm very happy that we tightly regulate the food service industry. i responded to this thread to give a little perspective. lemonade stands aren't being targeted for no reason by mean authoritarians who want to ruin a childhood rite of passage. there are legitimate reasons behind an increased awareness and enforcement of food safety issues.