50A hook-up has almost 4x as much power available as 30A, so in comparison 30A is very restrictive. It's rather easy to exceed 30A if you don't practice some restraint. For example, one a/c unit draws about 12 amps when running and briefly much more each time the compressor cycles on. If your water heater is in electric mode, that's another 12 amps whenever it is heating. The fridge in electric mode is 2-3 amps and a microwave is typically 10-3 amps. A hair dryer is typically 10-15 amps, coffee makers 3-5 amps, etc. As you can see, it's not difficult to exceed 30A total if multiple of those items happen to be active at the same time. The fact that most of them are controlled by thermostats makes it hard to predict when the 30A circuit breaker might trip.
Most people cope by operating the water heater and fridge in LP gas mode, using only one a/c unit, and avoiding smaller electric appliances as much as possible.