I did a lot of channel crossings in a UK registered vw transporter (2009 to 2019) and used to be stopped the majority of the time coming into the UK from France/Belgium/Holland. Most of the time the customs would want the side and rear doors opening to check for hidden people, and that was it.
Going into the UK one time, one UK customs guy asked about knives, so I told him I had kitchen and "workshop" knives, and he wanted to see them all, then he wanted to take them all. I argued with him and eventually convinced him that I was using them for kitchen and workshop reasons. I then showed him my ice axes and had to explain to him that they were sport equipment. I didn't have to hand them over, but he wasn't happy. I was 45 at the time, and had work suits in the van, which might have convinced him I wasn't the UK version of a gang banger.
I did forget to tell him about the hand axe.
I'd also get stopped and searched very often going into Switzerland (where I worked) travelling in from Germany (skiing). They'd be very professional, check my documents, open the doors, thank me and let me go.
I was stopped twice in one day in Germany once, they were very professional both times.
The day after the Bataclan terrorist attack I was parked up on a German autobahn lay-by during the day having a travel snooze, and "knock knock", had 2 police go through the van in quite a detailed manner. The younger cop wanted to check every little hidey hole for (presumably) drugs, whilst the older cop just checked for hidden people, checked my documents and then got got the younger cop to stop so that they could leave and presumably check for more fleeing/travelling terrorists. They were very polite and professional.
Apart from those times, I've never been stopped.