Giving alcoholic beverages to children this age is dangerous. Their small body size makes them more likely to become intoxicated. They can also be harmed by low blood sugar as a result of the alcohol. Caffeine is not as dangerous (and is also found in sodas), but toddlers simply don't need it. If they are thirsty, water is the best drink.
In addition to the immediate risk of alcohol, giving wine and beer to a child can lead to a worrisome pattern. Several studies have shown us that younger teens who begin drinking have a much higher rate of alcoholism later in life. A family can help protect their child by delaying the onset of drinking.
You are quite right to tell friends and relatives "No" to alcohol for your child. Keep up the good work.