Your results sound completely normal for two radios operating simplex, antennas at 4-7’ AGL, and with loads of obstructions.
Midland’s lure of “38-Mile Range” is worse that saying “You too could win the lottery”. In the real world you are more likely to win the power-ball lottery 6 times before you would ever experience 38-mile range with their walkie talkies.
Obstructions are the enemy of range in radio communications. Never underestimate how much they negatively effect range and don’t accept any statements to the contrary.
Two GMRS handhelds will have a range of 6-miles if used on row boats over smooth water until the earth (water) becomes the obstruction and the signal is lost. That assumes both people are standing in the boat and holding radios at 6 feet AWL. If both people now sit in the boat, range will drop to about 3 miles until the earth becomes the obstacle again. Do an internet search on ‘Radio Horizon’ to see how this works. Also, here is a simple calculator to see what your best case scenario is: https://www.everythingrf.com/rf-calculators/line-of-sight-calculator.
As you will learn, the earth is an obstacle that blocks your signal quite dramatically. If there are hills between the two antennas, same thing. Hills are an earth obstacle. Now, if you go into a heavily treed area, or an urban area with lots of buildings everyone of these attenuates your signal to some degree too. All of these add up to reduce your range further. Mix distance, hills and other obstacles and range is squashed.
You will hear over and over phrases such as “Height is might”, “Height is King” and “Height is everything”. This is true for a couple of reasons. First, as each antenna goes up in elevation the radio horizon gets further and further way, so your theoretical maximum range on earth increases. Second, when you raise the antennas up, often the number and density of obstacles between the antennas drops too so your real-world range increases.
My simplex HT to HT range and HT to Mobile ranges mimics yours. However, when I use mobile to base communications with base antenna at 40’ I loose communications at around 4 miles. When I raise it to 56’ I loose all communications around 8 miles. Yet with both my base and mobile rights I can communicate with repeaters 22-50 miles away because the repeater antennas are so much higher than mine are. Higher antennas mean fewer obstacles, thus increased range.