I'll mostly go along with that but add that some folks have limitations!

However, a DIYer can definitely do a laser alignment if they have a properly working brain and a wish to do it.
I use two laser levels, (kinda like a short spirit level) cheaply purchased. One for each wheel.
The BRP method of mounting laser levels on the brake disc is prone to minor errors but doable. For ease, I checked out the accuracy of my wheel rims and found them to be surprisingly accurate so this made the job much simpler.
I do the toe-in using the wheel rim diameter so it's always a fixed dimension and easily repeatable.
The toe-in measurement I've settled on is 4mm and has proved to be fine. However, I use modified, more rigid steering tie-rods to remove the flexibility of the originals since that flexing allows variable toe-in dependent on cornering forces.
But, the important bit... Once the lasers are attached to the wheels or brake discs, the toe-in measurement can be taken by moving the target the same distance as the wheel rim diameter. Read that again...
So, for the target I use a piece of nice flat board fastened to a batten of wood so that it will stand on its own. The lasers are mounted on the Spyder and the laser beams checked by measuring vertical height at a distance to be sure they are parallel to the floor and at wheel centre height. A few feet in front of the Spyder I chalk two parallel lines on the floor with a distance between them of the wheels rim diameter. The lines are at right-angle to the centre of the Spyder. The target board is placed on the line closest to the Spyder and the centres of the laser dots is marked. The board is then moved to the next line on the floor, one marked dot line is aligned with one laser dot. The toe measurement it then the distance of misalignment between the second marked dot line and the actual second laser dot. Note that this can be toe-in or toe-out dependent on your present alignment.
The tie-rods are adjusted and the dots alignment repeated until it is at the desired setting. Then the rod nuts are locked taking care with the alignment of the tie-rods ends to each other on each tie-rod.
The BRP recommendation is to use a special tool to lock the steering arm and also to check the bar ends by measurement to the bodywork for the initial set up. Then BUDS is used to datum this info into the bike. However, provided there is little wear in the steering mechanism and the Spyder is not damaged, the relationship between the steering arm and the bars should stay fixed.
For the DIYer, it's good to take note of the bar measurement before starting so that it can be checked at the end of the procedure if considered necessary.
Requirements: a flat level floor, a flat target board, lines marked on the floor exactly at right-angle to the Spyder centre line and distanced apart by the wheel rim diameter, the Spyder should be centred on the floor marked centre line, both tie-rods must be adjusted equally each time a change of adjustment is done and, of course, two accurate laser levels.
As usual, things sound more complicated when written than they actually are in practice.