Keeping the neighbor kids and stray dogs off your property and keeping people out of a country is not comparable. You might argue that your hedge keeps murderers, burglars, rapist and vandals out, but I doubt a hedge or fence or even a residential wall is all that effective. Like I said fences mainly keep things in, including your privacy.
Idealistically, I am not against controlling illegal immigration. I don't support Trump's wall because I doubt it will do much good or that it will even be completed. What's more, it is costing taxpayers dearly.
It hurts the brain of a logical person to see this kind of argument. You understand the wall is far less than importing millions that are unskilled and likely to be on govt benefits long term? How do you not think of that before you say something like the wall is more expensive?
The saying is "you lock your stuff up to keep honest people out". Another saying is "fences make good neighbors". These are time tested adages.
Illegal immigration by definition is people breaking the law, criminals, cartels, etc. AKA bad neighbors. AKA dishonest people.